Final answer:
The cost of postage for a 3-ounce letter is $0.56, calculated by summing up the cost of the first ounce ($0.22) and the additional ounces ($0.34).
Step-by-step explanation:
The student's question pertains to calculating the cost of postage for a letter weighing 3 ounces when the cost is $0.22 for the first ounce and $0.17 for each additional ounce. To solve this, one must add the cost of the first ounce to the cost of the additional ounces. In this case, there are 2 additional ounces to be accounted for (3 oz - the first oz).
Calculating the additional cost would involve multiplying the number of additional ounces (2) by the cost per additional ounce ($0.17). Therefore, the additional cost would be 2 x $0.17, which equals $0.34.
The total cost of postage would then be the sum of the cost of the first ounce and the additional ounces: $0.22 (for the first ounce) + $0.34 (for the additional ounces), resulting in a total cost of $0.56.