Need help On this whole thing

7x+8y=-18, 4x-9y=-3 solve the system of equations

Identify the converse of the following conditional: if a point is in the first quadrant, then its coordinates are positive. if the coordinates of a point are not positive, then the point is not in the first quadrant. if the coordinates of a point are positive, then the point is in the first quadrant. if a point is in the first quadrant, then its coordinates are positive. if a point is not in the first quadrant, then the coordinates of the point are not positive.

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