7. feladat megoldása
(+ | 4) |
|
(– | 9) | = | + | 4 | – | 9 | = | – | 5 | |||
(+ | 1) |
|
(– | 7) | = | + | 1 | + | 7 | = | + | 8 | |||
(– | 5) |
|
(+ | 4) | = | – | 5 | – | 4 | = | – | 9 | |||
(– | 8) |
|
(– | 7) | = | – | 8 | – | 7 | = | – | 1 | 5 | ||
(+ | 9) |
|
(+ | 2) | = | + | 9 | – | 2 | = | + | 7 |