pls help with algebra homework

Question

Suppose P=f(t)  is the population (in thousands) of town t  years after 1990, and that  and f(3)=14 , and f(10)=20

Find a formula for f^-1(P)

f^-1(50)

Answer 1

Determine the equation of f(t) using the two-point form from Algebra 1

(y - 14) / (x - 3) = (20 - 14) / (10 - 3)