Multiply 10x3 10 x 3 by 1 1 to get 10x3 10 x 3 . Divide 15 15 by −3 - 3 to get −5 - 5 . Use the slope-intercept form to find the slope and y-intercept. The slope-intercept form is y=mx+b y = m x + b , where m m is the slope and b b is the y-intercept.