Question

A babysitter is trying to determine the ages of three children: Jerome, Keenan, and Leitha. She knows the following facts about their ages: the sum of Jerome’s and Keenan’s ages is 18 years; the sum of Jerome’s and Leitha’s ages is 19 years; and the sum of Keenan’s and Leitha’s ages is 21 years. How old is Keenan?

Answer 1

10 years.

Explanation:

Let Jerome, Keenan, and Leitha have ages of x,y and z respectively,.

Then given that x+y =18 ... i

x+z =19 ... ii

y+z = 21 ... iii

From the above information we are to find out y and i.e.Keenan age.

Add all the 3 equations

Left side becomes x+y+y+z+z+x = 2(x+y+z)

and right side becomes = 18+19+21 = 58

In other words, 2(x+y+z) = 58

Divide by 2

x+y+z =29 ... iv

From the equation iv subtract ii

x+z =19

We get y = 10

Hence Kennan age = 10 years