Question 951638
let t = Tom's age
let m = Melissa's age
I think when they refer to "these two siblings" they mean Tom and Mellisa
:
Tom is five years older than his sister Melissa,
t = m + 5
and 
three times the sum of the ages of these two siblings is two years more than five times the age of Tom.
3(m + t)= 5t + 2
3m + 3t = 5t + 2
3m = 5t - 3t + 2
3m = 2t + 2
Replace t with (m+5)
3m = 2(m+5) + 2
3m = 2m + 10 + 2
3m - 2m = 12
m = 12 yrs is Melissa's age
then
12 + 5 = 17 yrs is Tom's age
:
:
We can check this in the statement
"three times the sum of the ages of these two siblings is two years more than five times the age of Tom"
3(17+12) = 5(17) + 2
3(29) = 85 + 2