Question

Three of four nubers have a sum of 22, if the average of the four numbers is 8, what is the fourth number? How do I figure that out?

Answer 1

Let the four numbers be \(w,x,y,z\).

You know that the sum of three of these is 22. Let \(w,x,y\) be these three numbers.
\[w+x+y=22\]
You also know that the average of all four numbers is 8:
\[\frac{w+x+y+z}{4}=8\]
Substitute the first equation into this one:
\[\frac{22+z}{4}=8\]
Now you can solve for the fourth number, \(z\).

Answer 2

I honestly have not taken a math class in 6 years, and have forgotten how to solve even Please help?

Answer 3

\[\frac{22+z}{4}=8\\
4\cdot\frac{22+z}{4}=4\cdot8\\
22+z=32\\
22+z-22=32-22\\
~~~~~~~~~~~~~~~~~~~\vdots\]

Answer 4

so, z=10?

Answer 5

Yes

Answer 6

Thank you!

Answer 7

You're welcome!