Add the equations.3x-y=-5
7x+y=15
![Add the equations3xy5 7xy15 class=](https://us-static.z-dn.net/files/d50/2695a8ee17be10fe37872c49232b9798.png)
Step-by-step explanation:
it is like a regular addition of numbers. you add the different positions.
3x + 7x = 10x
-y + y = 0
-5 + 15 = 10
so, D. is the right answer : 10x = 10