jika f(x)=7/x+5 maka f-1(x) tolong bantu ya??

f(x) = 7 / (x + 5)
y = 7 / (x + 5)
y(x + 5) = 7
xy + 5y = 7
xy = 7 - 5y
x = (7 - 5y) / y

f^(-1)(x) = ( 7 - 5x) / x