Bonjour,
(3 - 2/3) / (4/3 x 7) =
(9/3 - 2/3) / (28/3) =
7/3 x 3/28 =
3/3 x 7/(7x4) = 1/4
(2/3)/(5/6) - 2/5 =
2/3 x 6/5 - 2/5 =
6/3 x 2/5 - 2/5 =
2 x 2/5 - 2/5 =
4/5 - 2/5 = 2/5
(-3/4 + 1/2) / (2/5 - 5/2) =
(-3/4 + 2/4) / (4/10 - 25/10) =
(-1/4) / (-21/10) =
1/4 x 10/21 =
(2 x 5)/(2 x 2) x 1/21 =
5/2 x 1/21 = 5/42