Your piggy bank has a total of 40 coins in it; some are dimes and some are nickels. If you have a total of $3.25, how many dimes do you have?

30

25

20

15

Question

Your piggy bank has a total of 40 coins in it; some are dimes and some are nickels. If you have a total of $3.25, how many dimes do you have?

 30

 25

 20

 15

anonymous · Answer

set up two equations. 
one for the coins 40= x+y
one for the amount 3.25 = .05 + .10y

anonymous · Answer

to make things easier for the amount multiply through by 10 just to get rid of the annoying decimals. it wont mess anything up.

anonymous · Answer

it's a system of equations
40 = d + n
3.25 = .05n + .10d

anonymous · Answer

25

anonymous · Answer

solution: 25,15
       Dimes, Nickels

anonymous · Answer

I got 15