Leveling two lights


I’m still a beginner with OH3 and scripting/Blockly. So i must ask. Actually i want to level out two lights in one room.
In detail. There are 2 Shelly Bulbs in my Floor which can get an Value from 0 to 100 for the Brightness. Now i want to have the second bulb folliow the brightness of the first one but inverted or say the difference between actual and 100. So, if the 1. has 100 (Full on) the second has zero (off), if the 1. has 50 the 2. should have 50 too, and so on. But i can’t find out how to do this “inverted” math in Blockly. The Valiue must be positive and can’t be more than 100 so all my ideas seems not to work. Can anyone help?

Isn’t there a subtraction block? If so, the solution seems easy: have a block calculating ‘100 - brightness of other bulb’ and send command with the result of the block.