Jawabanmu

2014-06-15T14:49:40+07:00
5,1 = {(n x 5) + (1 x 7)} / (n + 1)
5,1 = (5n + 7) / (n + 1)
5,1 (n + 1) = 5n + 7
5,1n + 5,1 = 5n + 7
0,1n = 1,9
n = 19 siswa
7 2 7