Answer:
[tex]m=20c[/tex]
Step-by-step explanation:
Let m represent the total money collected and c represent the amount of cars washed.
We know that the money collected is directly proportional to the number of cars washed. So, we can write the following equation:
[tex]m=kc[/tex]
Where k is a constant.
We know that the money collected after 7 car washes is $140. So, let's find our k by substituting 140 for m and 7 for c. This yields:
[tex]140=7k[/tex]
Find k. Divide both sides by 7:
[tex]k=20[/tex]
So, the value of k is 20.
We can now substitute k back into our direct variation equation:
[tex]m=20c[/tex]
This means that every car costs $20 to wash.
And we're done!
