Answer these 4 math questions using elimination method for 10 pts !

Solve these system of equations by the elimination method:
1) 7x+3y=-13
3x-y=-1

2) 5r-3s=13
2r-6s=-14

3) 6x-9y=19.5
7y-2x=-8.5

4) 5x+3y=38
3x+5y=42


i have a midterm tomorrow and i couldnt solve these 4 review questions can you please help me?

1)Multiple the 3x-y=1 by 3 so you can eliminate the y's, so now we have 7x+3y=-13 and 9x-3y=-3, add them together so the y's cancel and you get 16x = -16, x = -1, plug that in for x and you get y =-2

2)Multiply the 5r-3s=13 by 2 so the s's can cancel and you get 10r-6s=26 and 2r-6s=-14, this time subtract them since a negative - a negative is really adding and the 6s's cancel. so now you get 8r=40, r = 5, plug that in for r and s = 4

3)Multiply the 7y-2x=-8.5 by 3 so the x's cancel and you get 6x-9y=19.5 and 21y-6x=-25.5, add them together and you get 12y = -6, y = -.5 plug that in you get x = 2.5

4)Multiply the top one by 3 and the bottom by 5 to get common x's and you get 15x+9y = 114 and 15x+25y = 210 subtract and we get -16y = -96, so y = 6, plug that in and x = 4