If y varies inversely with x and y =5 when x=2.5 what is the value of y when x=20

If x = 20, then y = 12.5/20 = 0.625

Step-by-step explanation:

The pertinent relationship is y = k/x, where k is the constant of proportionality.

Subbing 5 for y and 2.5 for x yields 5 = k/2.5, so k = 12.5.

Then the specific relationship fit to this problem is y = 12.5/x.

If x = 20, then y = 12.5/20 = 0.625

x= cost per bracelet

number of bracelets * x + shipping charge = total cost

so

9x+9=72