Add these together.
You get -15y=-45
So y=3
Now plug in to first equation.
8x-8(3)=-16
8x-24=-16
8x=8 so x=1
Check both values in second equation.
-8(1)-7(3)=
-8-21=-29
It works...so x=1, y=3
A triangle, cut it straight down the middle and you get a triangle
10=a/2 + 7
First subtract 7 from both sides
3=a/2
Next multiple 2 on both sides, so that a is by itself
3(2)=a
A=6