Answer:
54 + 4D = L
After 39 days, the total length of the road will be 210 miles.
Explanation:
Given that a construction crew is lengthening a road, and the road started with a length of 54 miles, and the crew is adding 4 miles to the road each day, to write an equation in which L represents the total length of the road ( in miles), and D represent the number of days the crew has worked, and then use the equation to find the total length of the road after the crew has worked 39 days, the following calculations should be performed:
54 (initial length) + 4D = L
54 + 4D = L
Thus, if the crew worked 39 days, the equation would be applied as follows:
54 + 4x39 = L
54 + 156 = L
210 = L
Therefore, after 39 days, the total length of the road will be 210 miles.