Bonjour,
[tex]7.5n = 3.75n + 50[/tex]
[tex]7.5n - 3.75n = 3.75n - 3.75n + 50[/tex]
[tex]3.75n = 50[/tex]
[tex]n = \frac{50}{3.75} [/tex]
Vérification :
[tex]7.5 \times \frac{50}{3.75} = \frac{375}{ 3.75} = 100[/tex]
[tex]3.75 \times \frac{50}{3.75} + 50 = 50 + 50 = 100[/tex]