Question 530934
a = number of adult tickets sold
c = number of children ticks sold
a + c = 500 (given)
so
a = 500-c
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7.5a = value of the adult tickets sold
4c = value of the children tickets sold
7.5a + 4c = 3312.5
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substitute a = 500-c
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7.5(500-c) + 4c = 3312.5
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multiply by 10 to eliminate decimals
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75(500-c) + 40c = 33125
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37500 -75c + 40c = 33125
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-35c = -4375
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c = 125 child tickets
.
a = 500-c
a = 375 adult tickets
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Check the value to make sure this is the right answer.
4*125 = 500
7.5*375 = 2812.5
500+2812.5 = 3312.5
Correct.
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Answer:  375 adult tickets and 125 child tickets.
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Done.