The number is -10.4
First we need to define the terms so
n = a number
Next we want to rewrite the sentence in standard form
10(.5n + 6) = 8
Distribute the 10
10(.5n) + 60 = 8
5n + 60 = 8
Subtract 60 from both sides
5n = -52
Divide both sides by 5
n = -10.4
Now we can check but substituting -10.4 for n in the original equation
10(-10.4/2 + 6) = 8
10(-5.2 + 6) = 8
10(.8) = 8
8 = 8
This is true so we know that the number is -10.4