The points (10, 6) and (7, u) fall on a line with a slope of -4/3. what is the value of u?

u = 10

Explanation:
slope can be calculated using the following rule:
slope = (y2-y1) / (x2-x1)

We are given:
slope = -4/3
point (10,6) representing (x1,y1)
point (7,u) representing (x2,y2)

Substitute with the givens in the above rule and solve for u as follows:
slope = (y2-y1) / (x2-x1)
-4/3 = (u-6) / (7-10)
-4/3 = (u-6) / (-3)
-3 * -4 = 3 * (u-6)
4 = u - 6
u = 4 + 6
u = 10

Hope this helps :)