You need to make turn this information into slope intercept form: y = mx + b. The m is your slope, the b is your y-intercept. x and y represents the coordinates that the line passes through. Make y = 1, make m = -2, and make x = 2, and you will get: 1 = -2(2) + b. When you simplify, you get 1 = -4 + b, add 4 to both sides and you'll get 5. So my equation is y = -2x + 5. Remember the -2 came from the slope! To get b, substitute the (2,1) in for (x,y) in the equation.
