Bonjour
12/-5 + 11/20
= (12 x 4) / (- 5 x 4) + 11/20
= - 48/20 + 11/20
= - 37/20
-17/-36 - -5/-9
= 17/36 - (5 x 4) / (9 x 4)
= 17/36 - 20/36
= - 3/36
= (3 x - 1) / (3 x 12)
= - 1/12
2/-9 + -8/9
= - 2/9 - 8/9
= - 10/9
9/32 - -5/-8
= 9/32 - (5 x 4) / (8 x 4)
= 9/32 - 20/32
= - 11/32
13/64 + 5/8
= 13/64 + (5 x 8) / (8 x 8)
= 13/64 + 40/64
= 53/64
9/40 + 2/5
= 9/40 + (2 x 8) / (5 x 8)
= 9/40 + 16/40
= 25/40
= (5 x 5) / (5 x 8)
= 5/8.
