Question 693143

mark has twice as many quarters as nickles and 3 more dimes than nickles, he has $4.20 in all, how many of each does he have. we need formula to figure this out, my daughter is having horrible time with this, and it has been to long for me to remember.


Let amount of nickels, quarters and dimes he has, be N, Q, and D, respectively


Based on the given information, Q = 2N, and D = N + 3


From this, the following coin-value equation can be formed:
.05N + .25(2N) + .1(N + 3) = 4.2


.05N + .5N + .1N + .3 = 4.2


.65N + .3 = 4.2


.65N = 4.2 - .3


.65N = 3.9


N, or amount of nickels = {{{3.9/.65}}}, or {{{highlight_green(6)}}}


Amount of quarters = 2(6), or {{{highlight_green(12)}}}


Amount of dimes  = 6 + 3, or {{{highlight_green(9)}}}


You can do the check!!


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