awk --> math-operation in data-record and joining with second file data

Hi!

I have a pretty complex job - at least for me!
i have two csv-files with meassurement-data:
fileA

...
01/07/14,01:10:00,20960,1993,2122,2052,1960,1778,1568,1376,1367,1282,1161,1186,1013,921,708,645,536,441,354,336,323,348,375,203,117,109,84,49,58,34,33,26,16,10,7,5,4,1,4,1,0,0,0,1,0,1,0,0,1,0,0,0,10527,22,0,119,974.6,5,3.98,0,0,0,0,0,75,58.8,
3.299,2.773,29.5,26.6,199,0000 0000 0000 0000,0.842718,1.04962,0.93209,0.582942,1.57034,4.5951(#/cm263)
01/07/14,01:20:00,21235,1985,2100,2215,2114,1943,1838,1653,1554,1463,1444,1448,1305,1069,969,820,677,587,477,417,435,470,466,280,138,118,116,58,43,40,19,26,13,13,10,7,4,1,1,2,2,1,1,0,0,1,0,0,0,0,0,0,10742,8,0,132,974.7,4.99,3.97,0,0,0,0,0,75,
58.8,3.299,2.772,27,26.1,199,0000 0000 0000 0000,0.879983,1.08077,0.962225,0.626434,1.57077,4.99936(#/cm263)
01/07/14,01:30:00,24639,2239,2474,2576,2527,2426,2195,1947,1790,1853,1737,1680,1645,1367,1248,1075,868,708,614,564,540,517,586,412,185,149,142,77,68,39,37,28,20,12,9,8,5,9,2,0,2,2,2,1,0,0,0,0,1,2,0,0,12659,30,0,164,974.8,4.99,3.97,0,0,0,0,0,7
5,58.5,3.301,2.771,26.5,25.1,199,0000 0000 0000 0000,0.89578,1.09963,0.976291,0.626434,1.57876,5.95218(#/cm263)
01/07/14,01:40:00,25306,2285,2509,2715,2685,2614,2492,2215,2110,1967,1974,1986,1894,1691,1525,1245,994,868,723,648,608,677,725,500,193,151,164,98,52,56,38,37,22,10,8,8,7,1,3,4,2,1,3,2,0,0,0,1,0,0,0,0,12985,29,0,174,974.7,4.99,3.99,0,0,0,0,0,7
5,58.4,3.284,2.771,29,25.6,199,0000 0000 0000 0000,0.919853,1.11922,0.995875,0.626434,1.57731,6.4352(#/cm263)
01/07/14,01:50:00,22003,2115,2336,2370,2485,2356,2304,2041,2021,1967,1939,1953,1789,1610,1439,1189,1005,803,690,604,528,609,660,437,200,172,141,108,74,34,41,30,20,16,15,7,6,2,0,2,0,0,1,0,0,1,0,0,0,0,0,0,11683,14,0,158,976.1,4.97,3.99,0,0,0,0,
0,75,59,3.3,2.771,29,27,199,0000 0000 0000 0000,0.932305,1.12304,1.00107,0.67317,1.57366,5.86103(#/cm263)
01/07/14,02:00:00,23419,2252,2449,2529,2629,2618,2404,2225,2272,2208,2157,2095,1977,1810,1567,1305,1110,915,794,658,625,706,772,494,236,181,150,100,67,44,36,35,16,13,9,3,4,3,1,1,0,0,0,2,1,0,0,0,0,0,0,0,12339,25,0,172,975.4,4.99,3.96,0,0,0,0,0
,75,58.8,3.299,2.773,27,26.1,199,0000 0000 0000 0000,0.942454,1.12894,1.0082,0.67317,1.57104,6.34192(#/cm263)
01/07/14,02:10:00,26960,2511,2689,2820,2900,2753,2573,2419,2381,2316,2268,2219,2174,1934,1621,1419,1227,976,841,774,627,780,830,591,229,179,198,106,59,35,37,33,24,16,17,5,3,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,13432,46,0,191,975.6,5.01,4.02,0,0,0,0,
0,75,58.5,3.298,2.773,26.1,25.1,199,0000 0000 0000 0000,0.938614,1.12763,1.00614,0.67317,1.5745,7.0131(#/cm263)
....

fileB

...
07/01/2014,01:10,233.40,10.70,2,2,3,1,271020.0,223
07/01/2014,01:20,231.20,9.20,2,2,3,1,276540.0,223
07/01/2014,01:30,231.90,10.30,2,2,3,1,282720.0,223
07/01/2014,01:40,231.70,11.10,2,2,3,1,289380.0,223
07/01/2014,01:50,233.30,11.80,2,2,3,1,296460.0,223
07/01/2014,02:00,233.20,10.50,2,2,3,1,302760.0,223
07/01/2014,02:10,235.90,11.40,2,2,3,1,309600.0,223
...

fileA: in each record the sum of $4+$5+$6+$7 and the sum of $11+$12+$13+$14+$14+$16 should be calculated and be pasted under the csv-conditions at the end of the record.
after that step, the data-records of fileA and fileB should be joined after a check of date and time. priority has the date of fileA.
I try to do this job by a EXCEL-Script, but EXCEL is in this case not working reliable.
So i want to solve it in awk - i do some small jobs with awk, but herefor i have no idea how to start and transcript the challange - can someone help me?

Thanks in advance,
IMPe

Have you started with anything yet??

hi PikK45

no, i have not, because i have no idea, how i start in the right way. Should i put the data in a array... how do i calculate the data sum=$4+$5+$6+$6 and past it at the end - record by record.
and finaly, how to compare the date and time-marks of fileA and fileB and let the script decide, to join the record of fileB.
Can you please give me a hint,
thanks in advance
IMPe