7) they give you the variable of Y
y= -3x
plug that y into the first equation
-3x + -3x = 30
add the two terms since they're like terms
-6x = 30
to find x you need to divide 30 by -6
x = -5
8) it s A
$8.50 per hour is the same as 8.50x and plus the commission. I guess D can be correct but I think they want to keep it in order since they gave Greg's equation first then Kevin's
9) same thing the y is given to you. Plus in that to the first equation. cobine like terms and find X