Answer:
C) 7
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Work Shown:
Use the slope formula
m = (y2-y1)/(x2-x1)
Plug in the given slope we want m = -5/3 and also the coordinates of the points. Then isolate r
m = (y2-y1)/(x2-x1)
-5/3 = (2-r)/(r-4)
-5(r-4) = 3(2-r) .... cross multiplying
-5r+20 = 6-3r
-5r+20+5r = 6-3r+5r .... adding 5 to both sides
20 = 6+2r
20-6 = 6+2r-6 ....subtracting 6 from both sides
14 = 2r
2r = 14
2r/2 = 14/2 .... dividing both sides by 2
r = 7
The slope of the line through (4,7) and (7,2) should be -5/3, let's check that
m = (y2-y1)/(x2-x1)
m = (2-7)/(7-4)
m = -5/3
The answer is confirmed