Question

Sally is three times as old as Sam. The sum of their ages is 84. How old is Sally?

Answer 1

Answer:

Sally is 63

Step-by-step explanation:

Represent Sally's age by x and Sam's by  y.

Then x = 3y and x + y = 84.

Substituting 3y for x in the second equation, we get:

3y + y = 84, or 4y = 84, or y = 21.  Since Sally is 3 times as old as Sam, we multiply 21 by 3:  Sally's age is 3(21 years) = 63 years