Question

Martin is 6 years younger than his sister. The sum of their ages is no more than 22 years. What is an inequality that can be used to represent this situation where X represents martins sisters age

Answer 1

Let n be Martin's sister's age. Then Martin is n-6. So:
n+n-6≤22

2n≤28
n≤14
n-6≤8
The oldest Martin's sister can be is 14. 

Answer 2

sisters age = x

martins age = x-6

equation: x +(x-6) <=22

2x -6 <=22

2x<=28

x<= 28/2

x<= 14