Ten times the sum of half a number and 6 is 8

The number is -10.4

Explanation:
Assume that the number we are looking for is x.

Now, we want to get 10 times te sum of half the number and 6 and equate this expression to 8. Then we can solve for x

Let's take this step by step:
half the number is 0.5x
the sum of half the number and 6 is 0.5x + 6
10 times the sum of half the number and 6 is 10(0.5x +6)
10 times the sum of half the number and 6 equals 8 is 10(0.5x+6) = 8

Now we can solve for x as follows:
10(0.5x + 6) = 8
5x + 60 = 8
5x = 8 - 60
5x = -52
x = -52/5
x = -10.4

Hope this helps :)

I'm just guessing, but my answer would c. 0 to 300.