Micheal and Susan have a combined age of 17 years. Micheal is 5 years older than Susan

M+S=17

M=S+5

(S+5) + S=17

2S+5=17

2S=12

S=6

M=11

Let x be the unknown number which is the age of Susan

Susan's age: x

Michael's age: x + 5

Both total 17 years. The equation would be.

x + x + 5 = 17

2x + 5 = 17

Find x. Transfer 5 to the other side and change its sign

2x = 17 - 5

2x = 12

Find x. Divide both sides by 2.

2x / 2 = 12 / 2

x = 6 = > Susan's Age.

Michael's age: x + 5 = > substitute x by its corresponding value: 6 + 5 = 11.

To check.

Susan's Age + Michael's age = 17

6 + 11 = 17

17 = 17