Dodenrider3
24

# What is the y-coordinate of the solution to the system of equations? y = 3x -1 x- y= - 9

$y=3x-1 \\ x-y=-9 \\ \\ \hbox{substitute 3x-1 for y in the 2nd equation:} \\ x-(3x-1)=-9 \\ x-3x+1=-9 \\ x-3x=-9-1 \\ -2x=-10 \\ x=\frac{-10}{-2} \\ x=5 \\ \\ y=3x-1=3 \times 5-1=15-1=14 \\ \\ (x,y)=(5,14)$ The y-coordinate is 14.