X + y = 30
100x + 150y = 3500
x=30-y
100(30-y) + 150y=3500
3000-100y+150y=3500
50y=500
y=10 - билетов по 150 рублей
х=30-10=20 - билетов по 100 рублей
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4v99=33+4v99+4*3-4v99=33+12=45
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