54.(-1/5)4
=625.(-1/625)
=-1
6/7+(2/11-6/7)
=6/7+2/11-6/7
=6/7-6/7+2/11
=0+2/11
=2/11
6/7+(2/11-6/7)
=6/7+2/11-6/7
=6/7-6/7+2/11
=0+2/11
=2/11