(-3x+3y=-9)-(-3x+y=7)
-3x+3x+3y-y=-9-7
2y=-16
y=-8, making -3x+3y=-9 become:
-3x+3(-8)=-9
-3x-24=-9
-3x=15
x=-5
So the solution to this system of equations is the point (-5, -8)
difference is monthly customer fee= 15-10 = $5
difference in minutely charge = 0.08-0.06 = $0.02
minutes it takes for plans to cost same amount= 5÷0.02 = 250 min
It’s the last one! Hope this helps