a. 1/2 + 1/10 = 5/10 + 1/10 = 6/10 → simplification par 2 donc 6/10 = 3/5
b. 4/10 + 3/100 = 40/100 + 3/100 = 43/100
c. 3/100 + 8/1000 = 30/1000 + 8/1000 = 38/1000 = 19/500
d. 1/4 + 15/100 = 25/100 + 15/100 = 40/100 → simplification par 20 donc 40/100 = 4/5