Bonjour ;
Exercice n° 1 .:
A = 15/4 + 5/12 : 10/9 = 15/4 + 5/12 x 9/10 = 15/4 + 5/10 x 9/12
= 15/4 + 1/2 x 3/4 = 15/4 + 3/8 = 30/8 + 3/8 = 33/8 .
B = (4/5+ 7/10 ) : ( 5/6 - 5/8) = (8/10 + 7/10) : (20/24 - 15/24)
= 15/10 : 5/24 = 3/2 : 5/24 = 3/2 x 24/5 = 3/5 x 24/2 = 3/5 x 12 = 36/5 .