Complete the explanation about his error.

3 × 8 − 3 ÷ 3 = 24 − 3 ÷ 3
= 21 ÷ 3
= 7

How many credit hours will a student have to take for the two tuition costs to be equal? round the answer to the nearest tenth of an hour.

Acollection of coins has value of 64 cents. there are two more nickels than dimes and three times as many pennies as dimes in this collection. how many of each kind of coin are in the collection?

Math i have no idea how to do a and b