{y=x-4 y=-2x+5
Solving systems by substitution
y = x - 4
y = -2x + 5
Substitute the value of y given in the first equation
for the y in the second equation and solve for x.
y = -2x + 5
x - 4 = -2x + 5
x - 4 + 2x = -2x + 5
3x - 4 = 5
3x - 4 + 4 = 5 + 4
3x = 9
3x / 3 = 9 / 3
x = 3
Use that to solve for y in one of the original equations.
y = -2x + 5
y = -2(3) + 5
y = -6 + 5
y = -1
Use both of those values in the other equation to check your answers.
y = x - 4
-1 = 3 - 4
-1 = -1