if f(x)=10x+7/6x+3 what is the f inverse

y = (10x+7)/(6x+3)

now solve for x:
(6x+3)y = 10x+7
6xy+3y = 10x+7
(6y-10)x = 7-3y

x = (7-3y)/(6y-10)

now x is y^-1, so to express f^-1(x), that is

f^-1(x) = (7-3x)/(6x-10)