You are wrapping boxes for a fund-raiser. You have 80 large boxes. You need 2 and three-fourths feet of ribbon for each large box. Each roll of ribbon has 50 feet of ribbon.

a. To estimate, we can round 2 and three-fourths to 3. Then, we can multiply 3 by 80 to get an estimate of the total amount of ribbon needed:

3 ft of ribbon per box x 80 boxes = 240 feet of ribbon

b. To find the exact number of feet, we can multiply 2 and three-fourths by 80:

2.75 ft of ribbon per box x 80 boxes = 220 feet of ribbon

c. To find the number of rolls needed, we can divide the total amount of ribbon needed by the amount of ribbon per roll:

220 feet of ribbon ÷ 50 feet per roll = 4.4 rolls of ribbon

Since we cannot buy a fraction of a roll, we will need to purchase 5 rolls of ribbon to have enough for all 80 boxes.