select the correct answer.\nlucy is knitting a blanket and needs to buy some more yarn. at her local craft…

select the correct answer.\nlucy 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?\na. $49\nb. $56\nc. $70\nd. $140

select the correct answer.\nlucy 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?\na. $49\nb. $56\nc. $70\nd. $140

Answer

Answer:

C. $70

Explanation:

Step1: Find unit - price

First, check if the price is proportional. For 2 balls costing $7, unit - price $u_1=\frac{7}{2}=3.5$ dollars per ball. For 8 balls costing $28, unit - price $u_2 = \frac{28}{8}=3.5$ dollars per ball.

Step2: Calculate total cost

Since the unit - price is $3.5$ dollars per ball and Lucy needs 20 balls. The total cost $C=3.5\times20 = 70$ dollars.