Over two summers, ray saved $900 and $500. the polynomial 900x2 + 500x represents his savings at the beginning of the third year, where x is the growth factor. (the interest rate r is x - 1.) what is the interest rate he needs to start the third year with $1600 in savings?
a. 264%
b. 0.1%
c. 1.1%
d. 8.4%