bonjour

Didi   = x  chocolats

Momo  = x /2

Juju =   x /2 + 4

x + x /2 + x /2 + 4 = 24

2 x /2 + x /2 + x /2 + 8/2 = 48/2

4 x = 48 - 8

4 x = 40

x = 10

Didi = 10

Momo = 5

Juju =  9

A =  5 x - 2 x² + 15 - 6 x - 7 x + 1

=  - 2 x²  - 8 x + 16

B = 9 + 2 x + 7  - 10 x - 2 x²

=  - 2 x² - 8 x + 16