Answer: option d is the correct answer.
Step-by-step explanation:
The landscaper estimates that a set of plants can be installed in 6 hours by 12 workers.
Let h represent the number of hours and let w represent the number of workers. Assuming that the variables are inversely related, introducing a constant of variation, k, the expression becomes
h = k/w
Substituting h = 6 and w = 12 into the expression, it becomes
6 = k/12
k = 12 × 6 = 72
The expression becomes
h = 72/w
If the landscaper wants to finish a set of plants in 4 hours, the number of workers that he needs to bring to the job would be
4 = 72/w
w = 72/4 = 18
