First, let's simplify the expression within the parentheses:
(6.1/4 - 4.1/8) = (1.525 - 0.5125) = 1.0125

Now, we have:
1.0125 * 4 + 3 + 1/3 : 2 + 1/2

Next, perform the multiplication and addition:

1.0125 * 4 = 4.05

4.05 + 3 + 1/3 : 2 + 1/2

Now, let's simplify the expression involving division and addition:

1/3 : 2 = 1/3 * 1/2 = 1/6

Now we have:

4.05 + 3 + 1/6 + 1/2

Finally, combine the terms:

4.05 + 3 + 1/6 + 1/2 = 7.05 + 1/6 + 1/2

Now, find a common denominator to add the fractions:

7.05 + 3/18 + 9/18 = 7.05 + 12/18

Now, convert the fraction to a decimal:

12/18 = 0.6667

Therefore, the final answer is:

7.05 + 0.6667 = 7.7167