x+y=18

The slope-intercept form is y=mx+b, where m is the slope and b is the y-intercept.

y=mx+b

Subtract x from both sides of the equation.

y=18-x

Reorder 18 and -x.

y=-x+18

y=-x+18

Using the slope-intercept form, the y-intercept is 18.

b=18

Find the Y-Intercept x+y=18