72:8*7-(45:9+3*3:2

To solve the expression \( 72:8 \ast 7 - (45:9 + 3 \ast 3:2) \), I'll break it down step by step.

1. Calculate \( 72:8 \): \[ 72 \div 8 = 9 \]

2. Now calculate \( 9 \ast 7 \): \[ 9 \ast 7 = 63 \]

3. Next, calculate \( 45:9 \): \[ 45 \div 9 = 5 \]

4. Now, calculate \( 3 \ast 3 \): \[ 3 \ast 3 = 9 \]

5. Now, calculate \( 9:2 \): \[ 9 \div 2 = 4.5 \]

6. Combine the results of \( 5 \) and \( 4.5 \): \[ 5 + 4.5 = 9.5 \]

7. Now, complete the expression by subtracting \( 9.5 \) from \( 63 \): \[ 63 - 9.5 = 53.5 \]

So, the final result is: \[ \boxed{53.5} \]