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annan65
16.03.2020 •
Mathematics
A box contains 81 coins, only dimes and nickels. The amount of money in the box is $5.30. How many dimes and how many nickels are in the box?
The number of dimes is
The number of nickels is
Solved
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Ответ:
Step-by-step explanation:
Let d represent the number of dimes. Then 81-d is the number of nickels and the total value in cents is ...
10d +5(81-d) = 530
5d +405 = 530 . . . eliminate parentheses
d +81 = 106 . . . . . divide by 5
d = 25 . . . . . . . . . subtract 81; number of dimes
81 -d = 81 -25 = 56 . . . . . number of nickels
There are 25 dimes and 56 nickels in the box.
Comment on the method of solution
It usually works well to let the variable represent the amount of the highest-value contributor (dimes). This keeps the numbers positive as the solution progresses.
Ответ:
5 x 3= 15
2 x 2= 4
4 x 1/2= 2
15 + 2= 17
Step-by-step explanation: