This is actually a very easy question.
Multiply -5x+10y=10 by -2 because we want something common with the first equation and negative because we want to eliminate it later.
We get 10x-20y=-20
Then we cross out the 20y
And we are left with: -9x=22 and 10x=-20
Then we add them(both sides) and get x=2
And then we substitute it in whichever equation you want to
Add 18 on both sides
Then divide 20 on both sides
So we get x=2 and y=2!
Then you can substitute them back into both equations and check your work but I don't have time so bye. Hope that helps!!