You have to get a variable by itself like in here... Y is itself so in the other equation or we can say second one you just have to sub it in... Like
2x+5(-3x-2)=16
2x-15x-10=16
Now you just have to subtract 2 from 15, because of the same variable that is (x)
So -13x-10=16
Take 10 to the other side means add from the both sides, that will get you at
-13x=26
So now x= -2
Remember you added because it was -10 if it would be a positive 10 then you have to subtract it from both of the sides but since here it was negative so you just added them up
Hope i helped
