Pls help math

Allie answered 72% of the questions on her math test correctly. if she answered 18 questions correctly, how many questions were on the test?

If you have the following equation, 2/3x+5/6-x=2-3/4x what would you multiply each term by to get rid of all the fractions

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible