Final answer:
The landscape service charges a one-time fee and an hourly rate of $15. For 3 hours of work, it charges $75. To find the cost for 20 hours of work, we can use the given information to calculate the one-time fee and then find the total cost.
Step-by-step explanation:
To find out how much the landscape service charges for 20 hours of work, we need to determine the total cost. The landscape service charges a one-time fee, which we need to find, and an hourly rate of $15. We are given that for 3 hours of work, the total cost is $75. We can set up an equation to solve for the one-time fee, as follows:
$15/hour x 3 hours + one-time fee = $75
$45 + one-time fee = $75
Subtracting $45 from both sides gives:
one-time fee = $75 - $45 = $30
Now that we have the one-time fee, we can calculate the total cost for 20 hours of work:
$15/hour x 20 hours + one-time fee = $15 x 20 + $30 = $300 + $30 = $330
Therefore, the landscape service charges $330 for 20 hours of work.