Question

let a, b, c belong to G for some group G. abc = e
show cab = e also.

Answer 1

e is the idendity right ?
abc=e (multiply by c^-1)
abcc^-1=ec^-1........ but cc^-1=e cuz c^-1 is the inverse of c
ab(e)=c^-1
ab=c^-1 (multiply by c )
cab=cc^-1
cab=e done ^^

Answer 2

thank youu