complicado sistema de ecuaciones problema de la palabra

Question

En una feria del condado, los boletos de los adultos vendidos para$\$ 5.50$, senior citizens' tickets for $\$4.00$, y los boletos de los niños para$\$$. On the opening day, the number of children's and senior's tickets sold was 30 more than half the number of adults' tickets sold. The number of senior citizens' tickets sold was $?

Así es como lo solucioné, pero hice algo malo y no sé qué. $more than four times the number of children's tickets. How many of each type of ticket were sold if the total receipts from the ticket sales were$$14,970$ $$c+s=\frac 12a+30$$ $$s=4c+5$$ $ps

Answer 1

$$c+s=\frac 12a+30$$ $$s=4c+5$$ $$5.5a+4s+1.5c=14970$5$$$ 5.5a+16c+20+1.5c=149705.5a+1.75a+87.5+20=14970$%