Complete the equation of the line through (1,4) and (2,2)

You are given the points in which the line intercepts. Using this info, we can use these numbers to find the slope.

m = (y2-y1)/(x2-x11) = (2-4)/(2-1) = -2/1 = -2

Our end result we want is the point-slope intercept formula : y=mx+b

We are still missing b, the intercept, so pick either of the two points (it doesn't matter which) and plug them into the equation. I will use (1,4), but again you could use either.

4 = (-2)*1 + b
6 = b

So now your final equation for the line after plugging in b and m is

y = (-2)x +6