4V + 4M = 11
6V + 2M = 9,10 => 12V +4M = 18,20
18,20-11 = 12V + 4M - 4V - 4M
7,20 = 8V
7,20/8 = V
Donc V = 0,90€
4V + 4M = 11
4×0,90 + 4M = 11
3,60 + 4M = 11
4M = 11-3,60
4M = 7,40
M = 7,40/4
M = 1,85€
Vérification :
6V + 2M = 9,10
6×0,90 + 2×1,85 = 5,40 + 3,70 = 9,10€
Donc on a bien :
V = 0,90€
M = 1,85€
3ème bijou
5V + 3M = 5×0,90 + 3×1,85 = 4,50 + 5,55 = 10,05€
Le 3ème bijou coûte 10,05€.