c) | Ecris la somme sans parenthèses, puis effectue. |
(–
7) + (+ 4) = |
–
7 + 4 = – 3 |
(+
6) + (– 7) = |
6
– 7 = – 1 |
(+
21) + (– 10) = |
21
– 10 = 11 |
(+
5) + (– 17) = |
5
– 17 = – 12 |
(+
17) + (+ 14) = |
17
+ 14 = 31 |
(–
24) + (– 15) = |
–
24 – 15 = – 39 |
(–
21) + (– 33) = |
–
21 – 33 = – 54 |
(–
17) + (+ 21) = |
–
17 + 21 = 4 |
(–
11) + (– 13) = |
–
11 – 13 = – 24 |
(+
17) + (+ 21) = |
17
+ 21 = 38 |