Bonjour,
-3/8 - 5/12
-9/24 -10/24
= -19/24
-7/5 + 3/5*11/4
-7/5 + 33/20
-28/20 + 33/20 = 5/20 = 1/4
-9/(21/10) =
(-9 * 10)/ 21
-90/21 = -30/7
-5/6 * 4/6 -(3/4)/(1/-2)
(3/4)/(1/-2) = (3*-2) / (4*1) = -6 /4 = -3/2
-5/6 * 4/6= -20/36 = -10/18 = -5/9
-5/9 - (-3/2) = -5/9 + 3/2
-10/18 + 27/18 = 17/18