Question 282267
the other tutor showed you the right wayn tosolve it.
Let's see where you went wrong.
 5(7x-4y)=5(-3)
 35y-20y=-15,
This is where you went wrong. It  should be 
35x-20y=-15
You changed x to y

Now for the other equation
2(2x+5y)=2(-7)
should be 
4x+10y-14
not sure where you got this
14x-8y=-6
or this
-14x-35y=49

I also don't see what you were trying to do by multiplying the first by 5 and the second by 2. I can see multiplying the first by 5 and the second by 4 to remove the y term -20y and +20y