Question

The cost to mail a first-class letter is $0.13 for the first ounce. Each additional ounce costs $0.7. Fractions of an ounce are rounded up to the whole next ounce. How much would it cost to mail a letter that weighs 19.89 ounces?​

Answer 1

$13.43

Given: To mail a first-class letter, it costs $0.13 for one ounce. From then, the additional ounce's cost $0.7.

Hence, equation can be created:

y = 0.13 + 0.7(x) where 'y' is total cost, 'x' is additional ounces

Here,

additional ounces: 19.89 - 1 = 18.89 ounces
`\sf \underset{}{ \xrightarrow{ \text{ rounded to nearest ounce} } }` 19 ounces

Total cost: y = 0.13 + 0.7(19) ⇒ y = 13.43