3,52-(2,07+9:7,5)+4,2

Let's solve the expression step by step:

1. Start with the expression: \(3.52 - (2.07 + 9:7.5) + 4.2\)

2. First, we need to handle the division \(9:7.5\) (which is \(9 \div 7.5\)): \[ 9 \div 7.5 = 1.2 \]

3. Now substitute back into the expression: \[ 3.52 - (2.07 + 1.2) + 4.2 \]

4. Next, calculate the sum inside the parentheses: \[ 2.07 + 1.2 = 3.27 \]

5. Now substitute that back into the expression: \[ 3.52 - 3.27 + 4.2 \]

6. Perform the subtraction: \[ 3.52 - 3.27 = 0.25 \]

7. Finally, add \(4.2\) to the result: \[ 0.25 + 4.2 = 4.45 \]

So, the final result of the expression \(3.52 - (2.07 + 9:7.5) + 4.2\) is: \[ \boxed{4.45} \]