SOLUTION: The amount of sales tax varies directly with the cost of the purchase. If the sales tax is $2.40 on a purchase of $40.00, what would be the sales tax on a purchase of $60.50?

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: The amount of sales tax varies directly with the cost of the purchase. If the sales tax is $2.40 on a purchase of $40.00, what would be the sales tax on a purchase of $60.50?       Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 1152427: The amount of sales tax varies directly with the cost of the purchase. If the sales tax is $2.40 on a purchase of $40.00, what would be the sales tax on a purchase of $60.50?

Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
the sales tax is 2.40 wen the purchase is 40.00
the ratio of the sales tax is 2.40 / 40.00 = .06
of the purchase is 60.50, then the sales tax is .06 * 60.50 = 3.63
this could be solved by using the direct variation formula.
that formula says y = k * x
y = sales tax
x = purchase price
when sales tax is 2.4 and purchase is 40, the formula becvomes:
2.4 = k * 40
solve for k to get k = 2.4 / 40 = .06
k is the constant of variation.
when purchase is 60.50, the formula becomes:
y = .06 * 60.50
solve for y to get y = 3.63