Jawabanmu

2014-01-31T12:58:15+07:00
U3 = a+2b
U5 = a+4b
U7 = a+6b
U9 = a+8b
---------------------+
       4a+20b = 104
       a = (104 - 20b)/4
       a = 26 - 5b
U6 = a+5b
     = 26 - 5b +5b
     = 26
2014-01-31T15:04:17+07:00
U3 = a+2b
U5 = a+4b
U7 = a+6b
U9 = a+8b

       a = (104 - 20b)/4
       a = 26 - 5b
U6 = 26 - 5b +5b
     = 26