I am going to assume that x2 = x squared
So: X^2 + 3x -40
= (X+8)(X-5)=0
X+8 = 0
X= - 8
The other solution is X -5 = 0
X = 5
Therefore the solution set is {-8, 5}
Here, number of periods (years), n=5
Annual interest rate, i=0.05 (compounded yearly)
Present value/deposit, P=100
Future value of deposit = P(1+i)^n=100(1.05^5)=127.63 (to the nearest cent)
Answer: After 5 annual interest payments, Bob will have 127.63 in his account.