Don't understand everything is wrong on here that i did

Line cd passes through points c(1, 3) and d(4, –3). if the equation of the line is written in slope-intercept form, y = mx + b, what is the value of b? –5 –2 1 5

Triangle xyz has vertices x(1,3), y(0,0)

Determine which postulate or theorem can be used to prove that lmn =nmo