Answer:
The amount they charged to wash a car is $6 and vacuum a car is $2.
Explanation:
Given:
Trisha and Byron are washing and vacuuming cars to raise money for a class trip.
Trisha raised $38 washington 5 cars and vacuuming 4 cars.
Byron raises $28 by washing 4 cars and vacuuming 2 cars.
Now, to find the amount they charged to wash a car and vacuum a car.
Let the amount charged for washing a car be

And the amount charged for vacuuming a car be

So, the total amount Trisha raised:
.......(1)
And, the total amount Byron raised:

Now, to get the amount they charged to wash a car and vacuum a car we use elimination method:




Dividing both sides by 3 we get:

Amount charged to wash a car = $6.
Now, putting the value of
in equation (1) we get:



Subtracting both sides by 30 we get:

Dividing both sides by 4 we get:

Amount charged to vacuum a car = $2.
Therefore, the amount they charged to wash a car is $6 and vacuum a car is $2.