Question 1085923
q = number of quarters
d = number of dimes
p = number of pennies
<pre>
q = 7d                  (1)
p = 6q = 6(7d) = 42d    (2)
25q + 10d + p =  2951   (3)  (in units of cents)
</pre>

Using (1) and (2), we can express (3) in terms of 'd' only:

25(7d) + 10d + 42d = 2951
175d + 10d + 42d = 2951
227d = 2951
d = 2951/227 = 13  —>  q=7*13 = 91  —>  p= 6*91 = 546
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Ans:  Bob has saved 546 pennies.
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Check:  546 + 10(13) + 91(25) = 546 + 130 + 2275 = 2951   (= $29.51 ,  so its good)