Réponses

2014-09-20T14:46:43+02:00
Bonjour

a) (3/5 - 1/3) x 21/8 - 19/20
= (9/15 - 5/15) x 21/8 - 19/20
= 4/15 x 21/8 - 19/20
= 64/120 - 19/20
= 64/120 - 114/120
= - 50/120
= -5/12




b) (1+5/2 x 3/10) : (5/3 - 1/2)
= (1 + 15/20) : (10/6 - 3/6)
= (20/20 + 15/20) : (7/6)
= 35/20 : 7/6
= 35/20 x 6/7
= 210/140
= 3/2