You already have all you need. Just put in it the slope-intercept form: y=mx+b where m is the slope and b is the y-intercept so
y=7x-4
2(2,1)(14,10)
(4,2) - (14,10)= (-10, -8)
The coordinates of K are (-10, -8).
1 x 10. It is unlikely that someone will run 103 meters in a second, along with 1010.
