SOLUTION: Aquilla buys 50 stamps, some for 0.10cents and some for 0.20cents. If she spends $6.40 altogether, how many 0.10cents stamps does she buy?

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Question 963456: Aquilla buys 50 stamps, some for 0.10cents and some for 0.20cents. If she spends $6.40 altogether, how many 0.10cents stamps does she buy?
Answer by CubeyThePenguin(3113) About Me  (Show Source):
You can put this solution on YOUR website!
x = number of 10 cent stamps
y = number of 20 cent stamps

x + y = 50
10x + 20y = 640

20x + 20y = 1000
-10x - 20y = -640
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10x = 360
x = 36

She bought 36 10 cent stamps.