`G = [ ( (-5)/7 - 7/9 + 9/11 - 11/13) . (3 - 3/4)] : [ (10/21 + 14/27 - 6/11 + 22/39) : (2 - 2/3) ]`
` = [ ((-6435)/9009 - 7007/9009 + 7371/9009 - 7623/9009) . (12/4 - 3/4)] : [ (12870/27027 + 14014/27027 - 14742/27027 + 15246/27027) : (6/3 - 2/3) ]`
` = ((-13694)/9009 . 9/4) : (27388/27027 : 4/3)`
`= -6847/2002 : 6847/9009`
` = -9/2`
Vậy `G = -9/2`