The table below shows the charges for phone calls to a certain country.

The first 10 min or part thereof |
$3.20 |

Subsequent each 1 min or part thereof |
$0.40 |

What is the charge for 15 min and 20 seconds?

dollars

For the first 10 min, the charge is $3.20.

The subsequent 5 min and 20 seconds is counted as 6 min.

Then, the subsequent charges: 0.40 × 6 = 2.40

Thus, the total charges: 3.20 + 2.40 = 5.60