What is the expression in standard form for 4(2a)+7(-4b)+(3*c*5)

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?

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

What is the rate for one gallon of gasoline