resoudre de tete les équations suivantes : x + 42 = 78 x + 42 = 78 x - 28 = 14 x + 48 = - 29 x - 8,5 = 7 3 × m = 15 t × 5 = 3,5​

Réponse:

1. x + 42 = 78

x + 42 - 42 = 78 - 42

x= 36

2. x - 28 = 14

x - 28 + 28 = 14 + 28

x = 42

3. x + 48 = - 29

x + 48 - 48 = - 29 - 48

x = -77

4. x - 8.5 = 7

x - 8.5 + 8.5 = 7 + 8.5

x = 15.5

5. m = 5

6. t = 0.7