Final answer:
The total cost of 2 dozen iris bulbs at varying prices per half-dozen is calculated by adding the cost of each category. For the first and second half-dozen, costs are calculated at their respective rates, and each additional bulb is calculated at the $3 rate, resulting in a total of $90.
Step-by-step explanation:
The question involves performing calculations to determine the total cost of 2 dozen iris bulbs with varying prices per half-dozen. The first half-dozen costs $5 per bulb, the second half-dozen costs $4 per bulb, and each additional bulb beyond the first dozen costs $3 per bulb. To calculate the total cost, you need to add the cost of each category of bulbs.
For the first half-dozen, the cost is 6 bulbs × $5/bulb = $30. For the second half-dozen, the cost is 6 bulbs × $4/bulb = $24. Since we are buying 2 dozen, we then have a third half-dozen and a fourth half-dozen, both at the price of $3 per bulb. The cost for these additional bulbs is 12 bulbs × $3/bulb = $36. Adding all of these amounts together, we get a total of $30 (first half-dozen) + $24 (second half-dozen) + $36 (third and fourth half-dozen) = $90. Therefore, the calculation representing the cost of 2 dozen iris bulbs is $90.