Suppose y varies directly as x. if y=8 when x=24, what is the value of x when y=9

Asmall foreign car gete 42 miles per gallon and user 35 gallons on a trip. gasoline costs $1.05 per gallon. what was the cost of gasoline per mile driver?

Problem fathi wants to print out a pdf document that is 48 pages long. to save paper, he decides to print on both sides of each sheet and to print two pages on each side of the sheet. how many sheets of paper will he need?

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?