8x11=(8x10)+(1x10) how can I make it true?

Step-by-step explanation:

Let's call each wash and the wax.

We know by given that the car wash charges $8 per wash and $10 per wax, this can be expressed as

and

A certain day, the total sales were no more than $1300 and there were no more than 350 of either service.

This information can lead to the following system of inequalities

The image attached shows the solution to this sytem.

Remember that the solution is always the intersection between both shaded regions, in the image is marked with S.

Therefore, the answer to the question is