Pls . i never understood this rule.

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

Miranda is braiding her hair. then she will attach beads to the braid. she wants 1_3 of the beads to be red. if the greatest number of beads that will fit on the braid is 12,what other fractions could represent the part of the beads that are red?

Write the expression 7x^3-28xy^2 as the product of 3 factors