Step-by-step explanation:
HCF OF 20 30 and 40 by listing common factors :-
factors of 20 - 1,2,4,5,10,20
factors of 30 - 1,2,3,5,6,10,15,30
factors of 40 - 1,2,4,5,8,10,20,40
There are 4 common factors
i.e, 1,2,5 and 10
therefore,
the greatest common factor of 40,20 and 30 is 10