Bonjour,
15ac + 14ac = (15 + 14)ac = 29ac
23xy - 35xy = (23 - 35)xy = .......
2a² + 8a² = (2 + 8)a² = 10a²
7x² - 12x² = (7 - 12)x² = .......
7ab + 5ba = (7 + 5)ab = 12ab
9.8yz - 15zy = (9.8 - 15)yz = -5.2yz
11y² - 5 - 3y² + 13 = (11 - 3)y² - 5 + 13 = 8y² + 8
