Answer:
220
Step-by-step explanation:
220
First find x: y= -2x+4 so you take that and substitute it into your second equation -x+3(-2x+4)=-9 ---> -7x+12=-9 ---> -7x= 3 ---> x=-3/7
Now you can find y by substituting x: y=-2x+4 ---> y=-2(-3/7) +4 ---> y=
The slope of this line is 3/2.