funny mathematics by elders can you disprove it ?

one of the most hated subject from my childhood till the end of my last semester in engineering is maths not because i disliked it but i was weak in it because there were no one to teach it in a funny and understandable way... recently came across this funny clip it is said that the clip is of 1940's starring Pa Kettle, Majorie Main and Percy Kilbride though i don't know much about them i liked the way old couples disproved the simple maths posed by the man see the below clip and enjoy

and between what do you think will you agree with those old couples?