fractions: 5/15 - 6/18=... 2/1-1/4=... 6/8+10/15-10/12=... 2.1/3=... 3.2/5=... 12/15.5/6=... 7/10.3=... 14/9.6/5=... 2/9.4=... Merci beaucoup :)

5/15-6/18
=1/3-1/3
=0

2/1-1/4
=8/4-1/7
=7/4

6/8+10/15-10/12
=3/4+2/3-5/6
=9/12+8/12-10/12
=7/12

2*1/3
=2/3

3*2/5
=6/5

12/15*5/6
=2/3*1/1
=2/3

7/10*3
=21/10

14/9*6/5
=14/3*2/5
=28/8
=7/2

2/9*4
=8/9