Answer :
as 20=16+4
16=4(4)
therefore gcd is 4
for hcf
gcd×hcf=product of two numbers=20(16)
hcf=5(16)=80
16=4(4)
therefore gcd is 4
for hcf
gcd×hcf=product of two numbers=20(16)
hcf=5(16)=80