Let sister be s. Matthew, M
Matthew is 7years older than twice the age of his sister
M = 7 + 2s
13 = 7 + 2s. 7 crosses the equality to other side and becomes -7
13 - 7 = 2s
6 = 2s Divide both sides by 2
6/2 = 2s/2
3 = s
Sister is 3 years old.
If you see that 3x-3 and set it equal to x+7 then you will get this,
3x-3=x+7
Now solve for X. You will get 5.
Then you plug five in and get 12 For both sides and then multiply 12 by 4 and get 48.
You answer is 48.
Hope this helps you.
The perimeter is 44.5
The area is 72.25
