[tex] \left \{ {{4p+15c=53} \atop {4p+10c=38}} \right. [/tex]
[tex] \left \{ {{4p+15c=53} \atop {-4p-10c=-38}} \right. [/tex]
Le aduni
[tex]4p-4p+15c-10c=53-38[/tex]
[tex]5c=15[/tex]
[tex]c=3[/tex]
[tex]4p+45=53[/tex]
[tex]4p=53-45[/tex]
[tex]4p=8[/tex]
[tex]p=2[/tex]
