Final answer:
To determine the cost of 15 inches of wire when 18 inches cost 54 cents, we set up a proportion and found that 15 inches will cost 45 cents.
Step-by-step explanation:
To solve this problem, we will set up a proportion since we are working with a direct relationship between the length of wire and the cost. We are initially given that 18 inches of wire costs 54 cents. We want to find out how much 15 inches of wire will cost based on the same rate.
The proportion is as follows:
18 inches / 54 cents = 15 inches / x cents
To find the value of x, which is the cost of 15 inches of wire, we cross-multiply and solve for x:
18x = 54 * 15
x = (54 * 15) / 18
x = 45 cents
Therefore, 15 inches of wire will cost 45 cents.