aider moi SVP pour demain

2/4  = 1/2  

2/5+7/10 = 4/10+7/10 = 11/10

19/2-13/4 = 38/4-13/4 = 25/4
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1.25-0.75=0.5

0.4+0.7=1.1

9.5-3.25 = 6.25