21 divided by 4 equals 5 1/4

Yvaries inversely as x. y =12 when x=5. find y when x=4

Julia bought 7 hats a week later half of all her hats were destroyed in a fire. there are now only 12 hats left with how many did she start

Atest consists of 10 multiple choice questions, each with 5 possible answers, one of which is correct. to pass the test a student must get 60% or better on the test. if a student randomly guesses, what is the probability that the student will pass the test?