Help! Solve.

{y=x−75x+2y=7

Use any method.

(0, -7)

(7, 0)

(-1, -8)

(3, -4)

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

Pls never taught i’m really confused and i rlly need

Pleas ! i just cant seem to get it right! choose: congruent or proportional choose: cf or ce or bc choose: segment addition postulate or cpctc