A dog-walking service charges a flat fee of 10 dollars per visit plus 20 dollars for each … — ACT

A dog-walking service charges a flat fee of $10$ dollars per visit plus $20$ dollars for each dog walked. If a client was charged a total of $90$ dollars for a single visit, how many dogs were walked during that visit?

A
9
B
5
4Answer
D
7
E
60

Answer

The correct answer is

4

. The relation between the total cost and the number of dogs walked is

10 + 20d = 90

. Subtracting

10

from both sides yields

20d = 80

, and dividing by

20

yields

d = 4

Step-by-Step Solution

Set up the equation based on the scenario details.

Let

d

be the number of dogs walked. The total cost is represented by the equation

10 + 20d = 90

The total cost of

90

dollars consists of a flat fee of

10

dollars plus

20

dollars per dog walked.

Subtract the flat fee from both sides of the equation.

20d = 80

Subtracting

10

from both sides isolates the cost of walking the dogs.

Divide both sides by the per-dog rate to solve for

d

d = 4

Dividing by

20

yields the number of dogs walked.

Key Concept

Translating verbal descriptions of multi-step scenarios into linear equations and solving them.

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