Answer:
A. 20
Explanation:
Plug in the numbers
Simplify the equation
225 + b = 625
Subtract both sides by 225
625 - 225 = 400
Your equation should look like
b = 400
Because you squared it, now you have to get it back to the formula you started with first. To do this, just find the square root.
The square root of 400 is 20