Question

Write an equation for the following problem. Then solve the equation and answer the problem.

Find three consecutive integers whose sum is 21.

Answer 1

Let consecutive integers a-1; a; a+1, then

a-1+a+a+1=21

3а=21

a=7.

7-1=6; 7+1=8.

Answer: 6; 7; 8.

Answer 2

Let the 3 numbers be x, x + 1 and x + 2, So:-

x + x + 1 + x + 2 = 21

3x = 21 - 3 = 18

x = 18/3 = 6

The 3 numbers are 6, 7 and 8 Answer