Bonjour !
b)
3(x-2) = 6(x+4)
<=> 3*x-3*2 = 6*x+6*4
<=> 3x - 6 = 6x+24
<=> 6x-3x = -24 - 6
<=> 3x = -30
<=> x = -30/3 = -10
c)
7x - (5x+3) = 5(x-3) + 2
<=> 7x - 5x - 3 = 5x - 15 + 2
<=> 2x - 3 = 5x - 13
<=> 5x - 2x = 13 - 3
<=> 3x = 10
<=> x = 10/3
Voilà !