Bonjour,
F=2/3/5/6 -2/5
(2/3) /(5/6) = 2/3 *5/6
2/3 * 5/6 -2/5
= 10/ 18 -2/5
= 5/9 -2/5
=25/45 - 18/45 = 7/45
G=1/3 - 4/3*2/5
1/3 - 8/10
= 1/3 - 4/5
= 5/15 - 12/15 = - 7/15
E=60/7/-4/21
(60/7) / (-4/21)
= 60/7 * -21/4
= -1 260/ 28
= - 630/14
= -315/7
= -45