I don’t understand this I’m looking for x, y and z and explain it to me pls

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

What are the solutions of the equation? z^2 + 11z + 24 = 0 a. 8, -3 b. 8, 3 c. -8, -3 d. -8, 3

Acompany charges $0.10 for each letter engraved. bobby plans to spend no more than $5.00 on the engraving on a jewelry box. write and solve an inequality to find the maximum number of letters he can have engraved.