Translate the statement into an equation. then solve the equation. the sum of 8 and 3 times a number is 23.

The best way to solve this is to write it out part by part. 

The first part is "the sum of 8 and 3," which is (8+3)

The second part is "...times a number," so we have n(8+3)

Lastly, "...is 23," means n(8+3) = 23, so here's the equation. In order to solve for n, divide both sides by (8+3) so 23/(8+3) which is 23/11. So the "number" is 23/11. 

Let the number be x
8+3x=23
3x=23-8
3x=15
x=5
The number is 5

Volume = the base times the height. i’m not going your work for you, but this is all you need to know.