SOLUTION: Here is the question. A childs bank has only quarters and dimes, the total in the bank is $2.20. There are three times as many dimes as there are quarters. How many dimes are th

Algebra ->  Linear-equations -> SOLUTION: Here is the question. A childs bank has only quarters and dimes, the total in the bank is $2.20. There are three times as many dimes as there are quarters. How many dimes are th      Log On


   



Question 352667: Here is the question.
A childs bank has only quarters and dimes, the total in the bank is $2.20. There are three times as many dimes as there are quarters. How many dimes are there and how many quarters are there?
the solution is written in the book, but I do not understand how the answer came to be.
0.25x + 0.10(3x) = 2.20
0.55x = 2.20
0.55x = 2.20
____ ____
0.55 0.55
x = 4 quarters
3x = 12 dimes
How did they come up with that answer? PLEASE HELP ME.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I would have done it slightly different
I would say:
Let a = number of quarters
Let b = number of dimes
given:
(1) d+=+3q
(2) 10d+%2B+25q+=+220 (in cents)
Now, I substitute (1) in (2)
(2) 10%2A3q+%2B+25q+=+220
30q+%2B+25q+=+220
55q+=+220
q+=+4
and, since
d+=+3q
d+=+3%2A4
d+=+12
There are 12 dimes and 4 quarters