Word problems with money please help

Question

The value of a number of a number of dimes and quarters is $1.25. If the number of dimes was doubled and the number of quarters was increased by 5, the value would be $3.00. How many dimes and quarters are there? I got 0 quarters and 12.5 dimes. I think that is wrong. Please help

Answer 1

amounts in pennies , so no decimals

 

10D + 25Q = 125

 

10(2D) + 25(Q+5) = 300

 

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Distributive property

 

10D + 25Q = 125

20D + 25Q + 125 = 300

 

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Subtracts 125 from both sides

 

10D + 25Q = 125

20D + 25Q = 175

 

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Subtracts the first equation from the second equation:

10D = 50

D=5

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So per the first equation: 5 dimes and 3 quarters.

 

10 dimes and 8 quarters is in fact $3