Question

The formula for the amount with simple interest is A = P(1 + rt). Find r, if A = 224, P = 200, and t = 2.

Answer 1

Since you are given the formula, all you need to do is substitute the numbers into the equation and solve for r.
A=P(1+rt)
224=200(1+r(2))
224=200+400r
24=400r
r=.06

Then you can check to see if that is the right answer by plugging it into the equation
A=200(1+.06*2)
A=224