Respuesta :

sqdancefan

9514 1404 393

Answer:

  • 22 nickels
  • 18 dimes

Step-by-step explanation:

Let d represent the number of dimes (the higher-value coin). Then the number of nickels is 40-d, and the total value in cents is ...

  5(40 -d) +10(d) = 290

  200 +5d = 290

  5d = 90

  d = 18

  40 -d = 22

There are 22 nickels (and 18 dimes).

_____

Additional comment

If you write the equation in terms of the number of nickels (n), you end up with the equation -5n = -110. The formulation used above avoids negative numbers, which can be confusing for some people.

obialof001

Answer:

These kind of problems require that you deal both with the number of coins and their value. Knowing that there are 40 total coins allows us to write:

:

d+n=40

:

Knowing that there are 10 cents in each dime, 5 cents in each nickel, and a total of 290 cents ($2.90) in value for the 40 coins, we can write:

:

10d+5n=290

:

but since d=40-n, we can substitute:  10+(40-n)+5n=290

                                                              400 - 10n +5n=290

                                                               -5n= -110

                                                                n=22

Meaning that there are 22 nickels worth $1.10.

:

To check your answer, note that there are 40-22=18 dimes. And 18 dimes are worth, $1.80. 1.80 + 1.10=2.90

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