how do I know how to find the constant of the proportianlity
Lance is knitting a blanket and needs to buy some more yarn. At his local craft store, 2 balls of yarn cost $5 and 8 balls of yarn cost $20. What is the constant of proportionality in this direct variation situation?
A. 5/2
B. 2/5
C. 5
D. 2
To find the constant of proportionality, we can set up a proportion using the given information:
2 balls of yarn cost $5
8 balls of yarn cost $20
We can set up the proportion as follows:
2/8 = 5/20
To simplify this equation, we can cross multiply:
2 * 20 = 8 * 5
40 = 40
Since both sides of the equation are equal, we can see that the constant of proportionality is 5.
Therefore, the correct answer is C. 5.