Edith needs 65 yards of yarn to knit a baby hat and 580 yards of yarn to knit a baby blanket. A ball of yarn contains 420 feet of yarn. How many balls of yarn does Edith need to buy to make the baby hat and baby blanket?

  5

Step-by-step explanation:

There are 3 feet in a yard, so 420 feet is 420/3 = 140 yards.

The total number of yards Edith needs is ...

  65 yd + 580 yd = 645 yd

So, the total number of balls of yarn Edith needs is ...

  (645 yd)/(140 yd/ball) ≈ 4.61 balls

Edith needs to buy 5 balls of yarn to make her projects.