Répondre :
bonsoir
19/20 = ( 19 * 3 ) / (20 *3 ) = 57/60
1/2 = ( 30 * 1 ) / ( 2 * 30 ) = 30/60
2/3 = ( 2 * 20 ) / ( 3 *20 ) = 40/60
3/4 = ( 3 * 15 ) / ( 4 * 15 ) = 45/60
7 /15 = ( 7 * 4 ) / ( 15 * 4 ) = 28/60
bonne soirée
bonsoir
19/20 = ( 19 * 3 ) / (20 *3 ) = 57/60
1/2 = ( 30 * 1 ) / ( 2 * 30 ) = 30/60
2/3 = ( 2 * 20 ) / ( 3 *20 ) = 40/60
3/4 = ( 3 * 15 ) / ( 4 * 15 ) = 45/60
7 /15 = ( 7 * 4 ) / ( 15 * 4 ) = 28/60
bonne soirée