Question

There are four more nickels than dimes in a piggy bank. The total amount of money is $2.45. How many of each type of coin is in the bank?

Answer 1

you have 15 dimes and 19 nickles .. therefore you have 4 more nickles then dimes
because 15 time 0.10 = 1.50 and
19 times 0.05 = 0.95
then you take 1.50 + 0.95 = 2.45

Answer 2

If you had only nickels you will have 49 coins.
replacing two nickels by a dime keeps the amount same
so 0 dimes + 49 nickels = 5 dimes + 39 nickels = 10 dimes + 29 nickels ...
this should lead you to the answer

Answer 3

Let N = the number of nickels
Let D = the number of dimes

There will be two equations in two unknowns (N and D) to solve simultaneously.

D + 4 = N
10D + 5N = 245 --> This is equivalent to .10D + .05N = 2.45
---------------
Solve by substitution.

D = N - 4

10( N - 4) + 5N = 245
10N - 40 + 5N =245
15N - 40 = 245
15N = 285
N = 19 -----> 19 Nickels

D = N - 4
D = 19 - 4 = 15 ------> 15 Dimes

Check:

15 = 19 - 4

10 ( 15 ) + 5 ( 19 ) = 150 + 95 = 245 cents which is $2.45

Answer 4

thanks Directrix, this is it, and it makes sense.

Answer 5

Glad to help.