pouvez vous m'aider svp? 4°

A= 1-(3-2/5)+(1/2+7/5)
= 10/10 -30/10 + 4/10 + 5/10 + 14/10
=3/10

ex 1 :
a=1x5/1x5 -(3x5/1x5 -2/5) +(1x5/2x5 +7x2/5x2)
a=5/5 - (15/5 - 2/5) + (5/10+14/10)
a=5/5- 13/5 + 19/10
a=8x2/5x2 + 19/10
a= 16/10 + 19/10
a= 35:5/10:5=7/2