Question

An office girl buys 12cent and 8cent stamps. It she spends

$9.00 and buys 100 stamps, how many of each sort did
she buy? (Let the number of 12cent stamps be x. Using x write down how many 8¢ stamps there were. Now make
an equation and find x).
​

Answer 1

x=25

Explanation:

x+y=100 (y being number of 8¢ stamps)

12x+ 8y = 900

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y = 100-x

12x + 8y = 900

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12x + 8(100-x) = 900

12x + 800 - 8x = 900

12x - 8x = 900 - 800

4x = 100

x=25