please help me..cukup 1 nomer saja, nomer 4

Karena f(x) = g(x), maka:

1/(x + 7) = 4/(x + 1)
1(x + 1) = 4(x + 7)
x + 1 = 4x + 28
4x + 28 = x + 1
4x - x = 1 - 28
3x = -27
x = -27/3
x = -9