The sum of three numbers is 71. The second number is 9 more than the first, and the third is double the second

Question

Needs to be done. This homework is due tomorrow and I'm struggling

Answer 1

Hey James,

 

x + y + z = 71

 

x + (x + 9) + (2x + 18) = 71

 

4x + 27 = 71

 

4x = 44

 

x = 11

 

First number 11
Second number = 9 + 11 = 20
Third number = 2 x 20 = 40

 

Let's check it:

 

11 + 20 + 40 = 71

 

It works!!!

 

Therefore, 3 numbers are: 11, 20, 40.

 

I hope you understand how I did it.  Good luck to you.

 

P.S.  Not all answers will be an integer or whole number (just in case).  After you get an answer, see if it checks out even though it is decimal.  It could be the answer.

 

Answer 2

Set this up as a system of equations. There are three equations and three unknowns, so it can be solved.

 

Ask yourself: what do I know?

 

The sum of three numbers is 71: x+y+z=71

The second number is 9 more than the first: y=x+9

The third is double the second: z=2y

 

Can you solve it from here?

 

(x=11, y=20, z=40)