According to the unitary method, the cost of each postcard is $0.7.
Unitary method:
Unitary method is used to find the value of a unit from the value of a multiple and the value of a multiple from the value of a unit.
Given,
Claudia buys 12 postcards, 12 stamps, and 1 pen. The postcards cost twice as much as the stamps. The pen costs $14.10.
Here we need to find the cost of the postcard.
In the given question, we have two variables, the price of the postcard and the price of the stamp, since the price for the pen is known.
And we also have the total cost of the purchase that is $14.1.
Therefore, now we have to create an equation as shown:
=> (12 x postcards) + (12 x stamps) + pen = 14.1
This equation refers the total amount spent by Claudia, but here we know that each pen costs $1.5, therefore:
When we apply the value on the equation then we get,
=> (12 x postcards) + (12 x stamps) + 1.5 = 14.1
=> (12 x postcards) + (12 x stamps) = 14.1 - 1.5
Therefore, (12 x postcards) + (12 x stamps) = 12.6
Here we also know that the postcards cost twice as much as the stamps, Then it can be written as,
postcards = 2 x stamps
By apply this value on the equation then we get the value of the stamp as,
=> (12 x (2 x stamps)) + (12 x stamps) = 12.6
=> (24 x stamps) + (12 x stamps) = 12.6
=> 36 x stamps = 12.6
Then the value of on stamp is stamps = 12.6/36
Therefore, the value of the stamps is 0.35
When we apply these values, then we get,
postcards = 2 x stamps = 2 x 0.35 = 0.7
Therefore, each postcard cost $0.7.
To know more about Unitary method here.
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