Bonjour,

(2*2*55) /( 11*15*8 )

= (2*5) / (15* 4)

= (1*5) /( 15*2)

= 1/ 6

(21 *-2 *5)/ ( -4* 15*- 14)

simplifie tout de suite

= -3/12 = -1/4