AB - AC + 5B - 5C = A * ( B - C ) + 5 * ( B - C ) = ( A + 5 )*( B - C )
XY - XZ - Y + Z = - X * ( - Y + Z ) - Y + Z = ( Z - Y)*( 1 - X )
KM - K - 2M + 2 = K * ( M - 1 ) - 2 * ( M - 1 ) = ( K - 2 )*( M - 1 )
3X - 3Y - 2AX + 2AY = 3 * ( X - Y ) - 2A * ( X - Y ) = ( 3 - 2A )*( X - Y )