Math
posted by Kirk .
plumber needs four sections of pipe 2
7
8
feet long. Can this be cut from a 12 foot section? If so, how
much pipe will be left over? If not, why not?

The way you typed your numbers makes the values unclear.
Do you mean "four sections of pipe" 2 7/8 feet long? If so, then here is help.
Since 3 > 2 7/8, and 4 * 3 = 12, it can be done.
Remainder = 12  (4 * 2 7/8) = ?