Ihave been stuck on this question for a while plz

It costs 4.25 for 1 pound of roast beef. how much will it cost to purchase 2.5 pounds of roast beef? round to nearest cent

20 ! need which shows a difference of squares? 10y^2-4x^2 16y^2-x^2 8x^2-40x+25 64x^2-48x+9

Question part points submissions used suppose that 100 lottery tickets are given out in sequence to the first 100 guests to arrive at a party. of these 100 tickets, only 12 are winning tickets. the generalized pigeonhole principle guarantees that there must be a streak of at least l losing tickets in a row. find l.