Answer:
D = 20H
Step-by-step explanation:
The amount Troy (D, in dollars) charges to mow a lawn is proportional to the time (H, in hours) it takes him to mow the lawn.
Hence, we can write D = kH ......... (1), where k is a constant.
Now, given that Troy charges $30 to mow a lawn that took him 1.5 hours to mow.
So, from equation (1) we get
30 = 1.5k
⇒ k = 20.
Therefore, equation (1) becomes D = 20H (Answer)