7,5x+y-8,5x-3, 5y

To simplify the expression 7,5x + y - 8,5x - 3,5y, you need to combine like terms.

First, let's combine the x terms: 7,5x - 8,5x = (7,5 - 8,5)x = -1x or -x.

Next, let's combine the y terms: y - 3,5y = (1 - 3,5)y = -2,5y.

Now, we can rewrite the simplified expression: -x - 2,5y.