Think about the individual parts of the expression.
5b - a
5b equals 625. Therefore, 5b - a = 625 - a
Now you have 625 - a.
If 5a = 25, then what does "a" equal? Divide 5 from both sides to find out.
5a/5 = 25/5
a = 5
Therefore, 625 - a = 625 - 5
625 - 5 = 620
620 is the answer.
