Bonjour
Calculer :
20/28+3/14x4/9
= 20/28 + 12/126
= (20 x 9) / (28 x 9) + (12 x 2) / (126 x 2)
= 180/252 + 24/252
= 204/252
= (2 x 17) / (2 x 21)
= 17/21.