SOLUTION: The 30 coins in Danielle's piggy bank have a value of at least $1.74. The bank contains only nickels and dimes. What is the fewest number of dimes that could be in the bank?

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Question 888084: The 30 coins in Danielle's piggy bank have a value of at least $1.74. The bank contains only nickels and dimes. What is the fewest number of dimes that could be in the bank?
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Nickels and dimes cannot make $1.74; but they can make $1.75.

0.05n%2B0.1d%3E=1.75 and n%2Bd=30. You want the inequality to be expressed only in dimes.

n=30-d; substitute this.
0.05%2830-d%29%2B0.1d%3E=1.75
Divide members by 0.05.
30-d%2B2d%3E=35
30%2Bd%3E=35
highlight%28d%3E=5%29.

Many values of d will give at least $1.75, but the smallest is highlight%28highlight%28d=5%29%29.