Surface area & volume. HELP please I don’t know how to do this I need the steps if possible :(

Ateacher has $80 to buy workbooks. each work book cost $3. if she buys as many workbooks as possible, how much money does she have leftover? a) $2 b) $4 c) $6 d) $8

If rt is greater than ba, which statement must be true ?

Solve each quadratic equation by factoring and using the zero product property. x^2 - 8x + 30 = 3x