Répondre :
a)207/68 <== Déjà simplifier
b)720/1512 = 72 * 720 / 72 * 1512 = 10/21
c)272/833 = 17 * 272 / 17 * 833 = 16/49
b)720/1512 = 72 * 720 / 72 * 1512 = 10/21
c)272/833 = 17 * 272 / 17 * 833 = 16/49