114,9-(6,5y+18,1)=72,75

114.9-72.75=6.5у+18.1
6.5у+18.1=42.15
6.5у=42.15-18.1=24.05
у=24.05:6.5
у=3.7

114.9-72.75=6.5у+18.1 6.5у+18.1=42.15 6.5у=42.15-18.1=24.05 у=24.05:6.5 у=3.7