Răspuns:
Notez: Ana= a, Maria=m, Toma=t
adunam cele 3 ecuatii ⇒m+a+a+t+m+t=66+60+54⇒
⇒2m+2a+2t=180 ⇒ 2(m+a+t)=180 ⇒m+a+t=180/2 ⇒m+a+t=90
[tex]\left \{ {{m+a+t=90} \atop {m+a=66}} \right.[/tex] ⇒t=90-66 ⇒t=24 lei
[tex]a+t=60[/tex] ⇒ a+24=60 ⇒a=36 lei
[tex]m+t=54[/tex] ⇒m+24=54 ⇒m=30 lei
⇒Toma are 24 lei
Ana are 36 lei
Maria are 30 lei