To solve this expression, we need to follow the order of operations (PEMDAS).

First, we calculate 3/3 * 6 = 6Next, we calculate 5 * (-4/7) = -20/7Finally, we subtract 3.75 from the result of the previous calculation.

Calculating step by step:

6 - 20/7 - 3.75
= 6 - 2.857 - 3.75
= 6 - 2.857 - 3.75
= 3.143 - 3.75
= -0.607

Therefore, the final result of the expression 1 3/3 6, 5 (-4/7) - 3, 75 is approximately -0.607.