Matt is five years older than twice his cousin Andy's age. The sum of their ages is less than 35. Let x represent Andy's age.

Andy maximal age = 13.3

Matt maximal age = 21.7

I will translate the problem into 2 equation where X is Andy's age and Y is Matt's age.

Y+5 = 2X

Y = 2X-5

X+Y<35

From this equation, it is clear that you won't be able to find their age. But you can find maximal age of Andy and Matt by changing X+Y<35 into X+Y=35

Inserting the first equation to the second equation you will get:

X+Y=35

X + (2X-5) = 35

3X = 35+5=40

X=13.3

X+Y=35

13.3+Y=35

Y = 21.7