If A is four times greater than B, but A plus B equal 90, what are the values of A and B?

Question

I am super confused about this.

Answer 1

A=4B

A+B =90

4B + B = 90

5B = 90

B = 90/5 = 18

A = 90-18 = 72

A is 72, B = 18

72=4(18)

72+18= 90