(121121121121/212121212121)×(121212121212/212212212212)
=(121121121121/212212212212)×(121212121212/212121212121)
=121/212*(12/21)
=121/371
(121121121121/212121212121)×(121212121212/212212212212)
=(121121121121/212212212212)×(121212121212/212121212121)
=121/212*(12/21)
=121/371