Question

Your piggy bank has a total of 46 coins in it; some are dimes and some are quarters. If you have a total of $7.00, how many quarters and how many dimes do you have?

Answer 1

Ok, we need to set up two equations.
The first one will tell us how many total dimes and quarters you have.
The second one will tell us the value of a quarter, the value of a dime, and the total value.
Let's have d = # of dimes and q = # of quarters
d+q = 46
.10d+.25q=7.00

Are you following me so far?

Answer 2

yes

Answer 3

Ok, now we can use elimination, substitution, or graphing to solve this.
See if you can solve it, if you have any trouble let me know.

Answer 4

Ok so what I've done already is...
d=46-q
10(46-q)+25q=7
460-10q+25q=7
460+15q=7
15q=-453
and I got q=-30.2 and I don't think it's right...

Answer 5

Alright, I think what you did wrong here is when you changed the equation from
.10d+.25q=7.00
to
10d+25q=7
you forgot to move the decimal place over two on the 7 aswell.
So the second equation should be
10d+25q=700
Now try solving it. :)

That was good that you noticed that your problem didn't make sense. If it doesn't make sense, it probably isn't right!

Answer 6

OHHH I FORGOT THE DECIMALS!!!

Answer 7

It happens. Those decimals are tricky. :)

Answer 8

16 quarters?