Answer:
9y-y-7y+3= y+3
Explanation:
Any time there is no number in front of a variable, it's automatically 1, you just don't put the 1 there. So it would be
9y - 1y= 8y
So after you do that, you take the 7y and subtract it from 8y
8y - 7y= 1y
And remember you don't put the 1 so it simplifies to just y.
You simply add or subtract all the numbers with the same variable
I'm not the best at explaining so if you have any questions on it I can answer them in the comments :)