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
![x.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/mmi228653dkvma4dszwy75q6dvkduzr4zg.png)
And the amount charged for vacuuming a car be
![y.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/gcglyt0bd2c9ftxzcnzvksi0ue28vql4ne.png)
So, the total amount Trisha raised:
.......(1)
And, the total amount Byron raised:
![4x+2y=28.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/8nssc03eucr7mnlm0fqm7bnyg7c4xxh2ro.png)
Now, to get the amount they charged to wash a car and vacuum a car we use elimination method:
![5x+4y=38\\4x+2y=28......* 2](https://img.qammunity.org/2021/formulas/mathematics/middle-school/vbf8bbv9npezthck4wo7ndd2bcod72odbe.png)
![5x+4y=38\\8x+4y=56](https://img.qammunity.org/2021/formulas/mathematics/middle-school/kiy6fgjo19pq1tel9xzb9vufyr46c82knj.png)
![-3x=-18](https://img.qammunity.org/2021/formulas/mathematics/middle-school/116b42l6h47jsi87tg3lhd6wcgpvydyidq.png)
![3x=18](https://img.qammunity.org/2021/formulas/mathematics/middle-school/uped9xjlebijad3dxqfriw7ecc2h6qh4ia.png)
Dividing both sides by 3 we get:
![x=6.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/5rw0kltwqln2fg7jbq8g8rko0nbcrl9giw.png)
Amount charged to wash a car = $6.
Now, putting the value of
in equation (1) we get:
![5(6)+4y=38.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/q7akq2jb8qiq4ym1giuk5hqcweuf76wvl4.png)
![5* 6+4y=38](https://img.qammunity.org/2021/formulas/mathematics/middle-school/v81p0mttv5wf5k74lcrz2v9wnhfj12w0tr.png)
![30+4y=38.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/tzls2v40fvhr3hbjlah5p2aj39avnmg2g9.png)
Subtracting both sides by 30 we get:
![4y=8.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/n1cf6vwdah24g0oh21hhliut1q6juy0uvh.png)
Dividing both sides by 4 we get:
![y=2.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/3s6h4i249n3u2t7ihpfy2hehyooric5ca6.png)
Amount charged to vacuum a car = $2.
Therefore, the amount they charged to wash a car is $6 and vacuum a car is $2.