Question

the sum of three numbers is 55. the second number is twice the first and the third number is five less than the second. What are the three numbers?

Answer 1

Let the first number be = x

Then the second number = 2x

The third number = 2x - 5

Their sum = 55

This can be written in an equation as =

x + 2x + 2x - 5 = 55

= x + 2x + 2x = 55 + 5 ( transposing -5 from LHS to RHS changes -5 to +5 )

= x + 2x + 2x = 60

= 5x = 60

= x = 60 ÷ 5 ( transposing ×5 from LHS to RHS changes ×5 to ÷5 )

= x = 12

The first number = x = 12

The second number = 2x = 2 × 20 = 24

The third number = 2x - 5 = 24 - 5 = 19

Therefore , the three numbers are 12 , 24 and 19 .