Can anyone with this? idk how to find the adjacent side.

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

Find the roots of the polynomial function f(x) = x^3 + 2x^2 + x

The price of a visit to the dentist is calculated according to the formula 50+100n50+100n where nn is the number of cavities the dentist finds. on your last visit to the dentist, 22 cavities were found. what was the cost of your visit?