How do I solve such questions without reverse plugging in the answers into the question itself?
First, I will exclude all answers which are not multiple of fives, based on the statement "five times the age..."
Second, I will take the oldest child age + 2 and check if it is twice of the middle child age.
How do I represent these word problems in algebraic equations?
Mary has three children. The oldest child is five times the age of her youngest, and in two years will be twice as old as the middle child.
Which of the following ages could the oldest child be?