One number is 3 times a first number. A third number is 100 more than the first number. If the sum of the three numbers is 215, find the numbers.

23, 69 and 123

Step-by-step explanation:

let the first number be x then the second number is 3x (3 times the first) and the third number is x + 100 (100 more than the first number)

The sum of the three numbers is

x + 3x + x + 100 = 215

5x + 100 = 215 (subtract 100 from both sides)

5x = 115 (divide both sides by 5)

x = 23

The 3 numbers are

x = 23, 3x = 3 * 23 = 69 and x + 100 = 23 + 100 = 123