Lucy is knitting a blanket and needs to buy some more yarn. at her local craft store, 2 skeins of yarn cost $7 and 8 skeins of yarn cost $28. what is the constant of proportionality in this direct variation?

a: 7/2

b: 2/7

c: 7

d: 2

The correct answer is A. 7/2

Step-by-step explanation:

Cost of 2 skeins of yarn at the local craft store= US$ 7

Cost of 8 skeins of yarn at the local craft store= US$ 28

What is the constant of proportionality in this direct variation?

Let's evaluate the first option:

Price per skein = Price / number of skeins

Price per skein = 7 / 2

Price per skein = US$ 3.50

Let's evaluate the second option:

Price per skein = Price / number of skeins

Price per skein = 28 / 8

Price per skein = US$ 3.50

As we can see the price is the same for both options, US$ 3.50, that expressed in a fractional number is 7/2. Therefore, the correct answer is A. 7/2