Use the substitution method to solve the following pair of simultaneous equations.
x+3y=4
y=2x-1

x + 3y= 4

-2x+ y= -1 (-2x from the other side)

2x+ 6y= 8 (multiply by 2)

-2x+ y= -1

7y =7

y= 1

x+ 3(1)= 4 (you do this to find the y)

x+ 3= 4

x= 1 (-3 from the other side)

x= 1 y=1   (1,1)

jbankston is right, use thhe link and you should find the answer.

parallel lines have the same slope. so if the green line has a slope of -4, the slope of the red line is also -4.