Выражение m + n\36 : m^2 - n^2\9b^2

( m + n )/36 : ( m^2 - n^2 )/9b^2 = ( m + n )/36 • 9b^2/( ( m - n )( m + n )) = 9b^2 / ( 36•( m - n )) = b^2 / ( 4( m - n )) = b^2 / ( 4m - 4n )