Question

Daniel is going to make 3 shelves for his father. His father gives him a piece of wood that’s 12m in length. He wants the top shelf to be half a foot shorter than the middle shelf, and the bottom shelf to be half a foot shorter than twice the length of the top shelf. How long will each shelf be if Daniel uses the entire 12m of wood?

Answer 1

Again the canned answer is wrong

Assuming you meant metres for all measurements .....
top --- x
middle = x - 1/2
bottom = 2x - 1/2

x + x - 1/2 + 2x - 1/2 = 12
4x = 13
x = 13/4 or 3.25

to shelf = 3.25
middle = 2.75
bottom = 6

Answer 2

The top shelf will be 5.5m long, the middle shelf will be 6m long, and the bottom shelf will be 11m long.