The triangle ADC and the triangle CDB are similar. Therefore:
Answer: A 4.5
31/50
31 ÷ 50 = 0.62
0.62 x 100 = 62%
So the answer is 62%
Hope this helps I didn't know if the 7k was apart of the problem or a typo
From the given table, the points can be written as : (6,7.55) , (12,7.85), (18, 8.15) and (24, 8.45)
Slope 
m = 
m = 0.05
slope intercept form of line = 
We plug m = 0.05, x = 6 and y = 7.55 and find c.

c= 7.25
Required equation:
... Answer