Bonjour,
e)2/7-5/3×27/35
= 2/7 - 54/105
= 30/105 -54/105
= -24/105 = -8/35
f)5/8+9/25÷18/15
= 5/8 + 9/25 * 15/18
= 5/8 +135/450
= 5/8 + 27/90
=5/8 + 3/10
= 50/80 + 24/80
= 74/80 = 37/40
g)2/7-5/3
= 6/21 - 35/21
= -29/21
h)1/4+3/5
=5/20 +12/20
= 17/20
I)5/36×9/25
= 45/900= 1/20
j)3/8÷4/5
= 3/8* 5/4
= 15/32