The amount Troy charges to mow a lawn is proportional to the time it takes him to mow the lawn. Troy charges $30 to mow a lawn that took him 1.5 hours to mow.

A. d = 20h

Step-by-step explanation:

Let the amount in dollars=d

Let the number of hours = h

Since the amount (d) Troy charges to mow the lawn is proportional to the time (h) it takes him to mow the lawn.

d=kh (k a variation constant)

Troy charges $30 to mow a lawn that took him 1.5 hours to mow.

d=$30, h=1.5 hrs

Substitution into the equation above gives:

30=k1.5

k=30/1.5=20

Substituting k=20 into the variation equation, we have:

d=20h