SOLUTION: How do you solve "mark has twice as many quarters as nickels and three more dimes than nickels. he has $4.20 in all. how many of each does he have? in system of equations form

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Question 681003: How do you solve "mark has twice as many quarters as nickels and three more dimes than nickels. he has $4.20 in all. how many of each does he have? in system of equations form
Found 2 solutions by funmath, josmiceli:
Answer by funmath(2933) About Me  (Show Source):
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +q+ = number of quarters he has
Let +d+ = number of dimes he has
Let +n+ = number of nickels he has
---------------------------------
given:
(1) +q+=+2n+
(2) +d+=+n+%2B+3
(3) +25q+%2B+10d+%2B+5n+=+420+ ( in cents )
---------------------------
Substitute (1) and (2) into (3)
(3) +25%2A%282n%29+%2B+10%2A%28n+%2B+3%29+%2B+5n+=+420+
(3) +50n+%2B+30+%2B+10n+%2B+5n+=+420+
(3) +65n+=+390
(3) +n+=+6+
and
(1) +q+=+2n+
(1) +q+=+2%2A6+
(1) +q+=+12+
and
(2) +d+=+n+%2B+3
(2) +d+=+6+%2B+3
(2) +d+=+9+
Mark has 12 quarters, 9 dimes, and 6 nickels
check:
(3) +25q+%2B+10d+%2B+5n+=+420+
(3) +25%2A12+%2B+10%2A9+%2B+5%2A6+=+420+
(3) +300+%2B+90+%2B+30+=+420+
(3) +420+=+420+
OK