A mother is x years old, her son is y years old and the sum of theirs ages together is 58 years. Five years ago, the mother was five times as old as the son. Write two equations in x and y and solve them to find the age of their mother and age of the son.

Question

I have found out the answer, but the problem is that I do not know the METHOD of finding the answer.
Please reply asap if you are able. Thank You.

Answers:

Mother = 45
Son = 13

Answer 1

the method is just to write the words as math:

mother is x years old, her son is y years old and the sum of theirs ages together is 58

x+y = 58

Five years ago, the mother was five times as old as the son

(x-5) = 5(y-5)

Now it's easy!

x+y=58
x-5y = -20

subtract and you get

6y = 78
y = 13
so, x=58-y = 45

5 years ago they were 40 and 8; 40=5*8

Answer 2

How do you get x-5y = -20