Zelma is 18 years older than her son she was three times as old as he was 1 year ago how how old are they now

Zelma´s age=x
(x-1)=Zelma´s age 1 year ago
son´s age=(x-18)
(x-18)-1=(x-19)=son´s age 1 year ago.
We have to solve this equation:
(x-1)=3(x-19)
x-1=3x-57
3x-x=57-1
2x=56
x=56/2
x=28

Zelma´s age=x=28
son´s age=(x-18)=28-18=10

Zelma is 28 years old and her son is 10 years old. 

Iwould say they are complementary because that’s the division of a 90 degree angle and it’s split between the middle of them