Question

Find the three consecutive number whose sum is more than 55 and less than 60.​

Answer 1

According to the question,

let x, x+1, and x+2 be those numbers, so that

x + x + 1 + x + 2 > 55, and

x + x + 1 + x + 2 < 60

or, 3x + 3 > 55, and

3x + 3 < 60

In otherwords,

55 < 3x + 3 < 60

By subtracting from 3, we get

55 - 3 < 3x + 3 - 3 < 60 - 3

or, 52 < 3x < 57

By dividing by 3, we get

52/3 < 3x/3 < 57/3

or, 17.3 < x < 19

or, 17 < x < 19 (approx.)

So, x should be greater than 17 and less than 19, which is x = 18

Therefore, the three consecutive numbers are x, x + 1, and x + 2, which are 18, 19, 20 respectively.

Answer 2

Step-by-step explanation:

According to the question,

let x, x+1, and x+2 be those numbers, so that

x + x + 1 + x + 2 > 55, and

x + x + 1 + x + 2 < 60

or, 3x + 3 > 55, and

3x + 3 < 60

In otherwords,

55 < 3x + 3 < 60

By subtracting from 3, we get

55 - 3 < 3x + 3 - 3 < 60 - 3

or, 52 < 3x < 57

By dividing by 3, we get

52/3 < 3x/3 < 57/3

or, 17.3 < x < 19

or, 17 < x < 19 (approx.)

So, x should be greater than 17 and less than 19, which is x = 18

Therefore, the three consecutive numbers are x, x + 1, and x + 2, which are 18, 19, 20 respectively.