Question

Lucy is knitting a blanket and needs to buy some more yarn. At her local craft store, 2 balls of yarn cost $7 and 8 balls of yarn cost $28. If Lucy needs 20 balls of yarn to finish the blanket, how much money will it cost? A. $49 B. $56 C. $70 D. $140

Answer 1

Using the proportion (2 balls / $7) = (20 balls / x dollars), we can solve for x:

2 * x = 7 * 20

Now, let's do the math:

2x = 140

To find the value of x, we divide both sides of the equation by 2:

x = 70

So, it will cost $70 to buy 20 balls of yarn. The answer is option C.