417*(2/10+13/990):(4/10+21/990)=417*(198/990+13/990):(396/990+21/990)=417*211/990:417/990=1/417*211/990*990/417=211/1=211
417*(2/10+13/990):(4/10+21/990)=417*(198/990+13/990):(396/990+21/990)=417*211/990:417/990=1/417*211/990*990/417=211/1=211