nuclear devastation

What if instead of the 15 and 21 Kiloton Little Boy and Fat-Man that dropped on the cities, America drops two 50 Kiloton Tsar Bomba's. What happens now?

So we should all know the shebang, Carter's femboy begging didn't deter the Iranians, but Ronald Reagan decided that he would be elected president, so decided to threaten to nuke the fuckers if they didn't hand the hostages over, infact, Reagan is the reason we have the 'nuked back to the stone...