Question

Two accounts earn simple interest. The balance yy (in dollars) of Account A after xx years can be modeled by y=10x+500y=10x+500. Account B starts with $400 and earns 5% simple annual interest.
a. Which account has a greater principal?

Question 2
How much greater is the principal? $

Question 3
b. Which account has a greater annual interest rate?

Question 4
How much greater is the annual interest rate?
%

Answer 1

1)
A has a greater principal

2) 
Principal of A is $500, the principal of B is $400, so A's principal is greater by $100

3)
Annual interest rate of A:
10/500 x 100
interest rate of A = 2%
The interest rate of B is higher.

4)
B's annual interest rate is 5% and A's annual interest rate is 2%, so B's is higher by 3%.