The sum of three numbers is 75. The third number is 2 times the first. The second number is 9 less than the first. What are the numbers?

Question

Mathematics

Shiloh

15 March, 16:32

The sum of three numbers is 75. The third number is 2 times the first. The second number is 9 less than the first. What are the numbers?

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Answers (1)

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Danielle · Answer 1

Let the three numbers be x, y and z. Then x+y+z=75.

z = 2x. y = x - 9.

Eliminate y and z by substitution: x + (x - 9) + (2x) = 75

Then 4x = 75 + 9, or 4x = 84. x = 21, y = 21 - 9 = 12, and z = 2 (21) = 42.

Check: Do 21, 12 and 42 add up to 75?