Use the distributive property and expand 28, then distribute the 4 to 20 and the 4 to 8. Then you have 18 + 80 + 32. Use commutative property to reverse the order of 32 and 80 so that 18 and 32 are friendly numbers to add.
First find the slope of your two points, then write your equation in point-slope form. Using your equation in point-slope form, you can solve and convert it to slope-intercept form.