-d/7=-13

can you help me solve for d

How do you answer this question? (step by step)

An initial investment of $100 is now valued at $150. the annual interest rate is 5%, compounded continuously. the equation 100e0.05t = 150 represents the situation, where t is the number of years the money has been invested. about how long has the money been invested? use your calculator and round to the nearest whole number. years

X+ y = 5 ; x - y =3 solve using linear combination