What is a type of expression that contains a variable

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?

Me. i can't figure out this question. give an explanation too. .

For what type of equity loan are you lent a lump sum, which is to be paid within a certain period of time? a. a line of credit b. equity c. a second mortgage d. an amortization