First we have to make y the same:
3x+y =-5 (times everything by 3)
7x+3y=1 (Times everything by 1)
Because both the signs are + you have to take away that’s a rule.
9x+3y =-15
7x+3y =1
(The 3y cancels out)
2x= -16
x=-8
We then take any equation of the two to find y I picked 7x+3y =1 you substitute the x with -8
7x+3y =1
7x (-8)+ 3y =1
-56+3y=1
(Add 56 to the other side)
3y= 57
y= 19
So x is -8 and y = 19
If you still unsure you can ask me I can explain again