Bonjour,
A)
3/10 +20/60
= 18/60 + 20/60
= 38/60 = 19/30
B)
9/14 *4/3
= 36/42 = 18/21= 6/7
C)
(45/12 +5/12 )/(10/9)
= (50/12 )/(10/9)
= (25/6) * 9/10
= 225/60 = 45/12 = 15/4
D)
(55/6 - 15/6) * 1/20
= 40/6 *1/20
= 20/3 *1/20
= 20/60 =2/6 =1/3
