Question

There are two numbers which add up to 20. If one number is five more than four times the other, find the numbers.

Answer 1

3 and 17

Explanation:

Let x and y represent the numbers.

x + y = 20 . . . . . . . . the numbers add up to 20

x = 5 + 4y . . . . . . . . one number is 5 more than 4 times the other

Substituting the second equation into the first:

(5 +4y) +y = 20

5y = 15 . . . . . . . . . . subtract 5

y = 3 . . . . . . . . . . . . divide by 5

x = 20 -3 = 17

The numbers are 17 and 3.