Ethan has $50 in a savings account. The interest rate is 5%, compounded annually. Which equation BEST models this situation to solve for savings (y) in x years?

HINT : This is a Exponential Growth and Decay problem.
A y = 50(1.5)
B y =50(1.05)
C y = 0.5(50)
D y = 50(x)^5

Last year, laura had $30,000 to invest. she invested some of it in an account that paid 7% simple interest per year, and she invested the rest in an account that paid 8% simple interest per year. after one year, she received a total of $2230 in interest. how much did she invest in each account?