Given
a=−11/27,b=4/9 and c=−5/18
a+(b+c)=(a+b)+c
Consider,
L.H.S.=a+(b+c)
=−11/27+{4/9+(−5/18)}
=−11/27+(4/9−5/18)
On simplification, we get
=−11/27+(8−5)/18
=−11/27+3/18
Taking L.C.M. we get,
=(−22+9)/54
=−13/54
R.H.S.=(a+b)+c
=(−11/27+4/9)+(−5/18)
On further calculation, we get
={(−11+12)/27}+(−5/18)
=(1/27)+(−5/18)
=(2−15)/54
=−13/54
Hence,
L.H.S.=R.H.S.