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

First, let's solve the multiplication and division within the parentheses:
5 4.5 = 22.5
8.9 4.5 = 40.05

Adding the results:
22.5 + 40.05 = 62.55

Next, let's add the fractions outside the parentheses:
1 + 11/15 = 15/15 + 11/15 = 26/15

Now, let's divide the sum of the parentheses by 3.75:
62.55 / 3.75 = 16.68

Finally, let's subtract 7/9:
26/15 + 16.68 - 7/9 = 52/15 + 16.68 - 7/9

If you need the final decimal result, you can simply perform the calculation.