(450/100:180/100-105/100)*240/100

To solve the expression \((450/100 : 180/100 - 105/100) * 240/100\), let's break it down step-by-step.

1. Simplify the divisions:
   • \(450/100 = 4.5\)
   • \(180/100 = 1.8\)
   • \(105/100 = 1.05\)
   • \(240/100 = 2.4\)

Now the expression looks like this: \[ (4.5 : 1.8 - 1.05) * 2.4 \]

2. Calculate the division \(4.5 : 1.8\): \[ 4.5 / 1.8 = 2.5 \]

3. Substitute that back into the expression: \[ (2.5 - 1.05) * 2.4 \]

4. Subtract: \[ 2.5 - 1.05 = 1.45 \]

5. Multiply by \(2.4\): \[ 1.45 * 2.4 = 3.48 \]

So, the final result is \(\boxed{3.48}\).