SOLUTION: if you have twice as many pennies as nickels and the total value of these coins is the same as the value of 28 quarters how many pennies do you have

That's one of these ten: 

2,4,6,8,10,12,14,16,18,20

out of these twenty: 

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19.20

That's 10 ways out of 20, so we make the fraction
 and reduce it to 
Answer: 

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That's one of these seven: 

1,2,3,4,6,8,12

out of these twenty: 

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19.20

That's 7 ways out of 20, so we make the fraction
 and it doesn't reduce
Answer: 

That's one of these eight: 

2,3,5,7,11,13,17,19

out of these twenty: 

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19.20

That's 8 ways out of 20, so we make the fraction
 and reduce it to 
Answer: 

Edwin