Aide moi svp exercice de math​

Bonjour

3(a + 7) => oui

= 3 * a + 3 * 7

= 3a + 21

7 + (2b + 3) => non

5 * (a x b) => oui

= 5 * a + 5 * b

= 5a + 5b

(x - 4) * 2 => oui

= x * 2 - 4 * 2

= 2x - 8

4(2 + x) => oui

= 4 * 2 + 4 * x

= 8 + 4x

6(2y - 1) => oui

= 6 * 2y - 6 * 1

= 12y - 6