Solve for y.
Move all terms not containing x to the right side of the equation.
Add 3 to both sides of the equation.
Add 18 and 3.
Divide each term by 2 and simplify.
Divide each term in 2x=21 by 2.
Cancel the common factor of 2.
Cancel the common factor.
Divide x by 1.
Since x=212 is a vertical line, there is no y-intercept and the slope is undefined.
y-intercept: No y-intercept