Dishwasher detergent is sold in individual packets. The 20 packet box sells for $5.49. The 60 packet box sells for $10.97. The 90 packet box sells for $18.95. Which is the best buy?

60 packets

Step-by-step explanation:

Given that :

Unit cost of 20 packets

$5.49 / 20 =$0.2745

Unit cost of 60 packets :

$10.97 / 60 = $0.1828333

Unit cost of 90 packets :

$18.95 / 90 = $0.2105555

The 60 packets has the least cost per unit, hence it is the best buy.

table 3 represents a direct variation function. : )