Set up an equation that relates the total cost of the post office with the total cost of shipping via UPS. Shipping via the post office entails a flat fee of $0.46 and a charge per ounce of $0.20. The total cost if shipped with the post office is then: 0.46 + 0.2(x-1), where x
represents the unknown number of ounces. The total cost of shipping with UPS is $3.45, regardless of the number of ounces.
The equation between the expressions is then:
0.46 + 0.2(x-1) = 3.45
Solve for x
x = 15.95
Meaning: for a package that weighs 15.95 ounces, the cost of the post office equals the cost of UPS. If the package weighs more than 15.95 ounces, shipping with the post office is more expensive. A weight below 15.96 ounces makes it cheaper to ship via the post office.