By solving an equation, we conclude that she will get 26 of the 15-cent stamps.
<h3>How many 15-cent stamps did she buy?</h3>
First, let's define the variables:
- x = number of 15-cent stamps bought.
- y = number of 31-cent stamps bought.
We know that she spends exactly $7, so we have the linear equation:
$0.15*x + $0.31*y = $7.00
Now we want to solve this for x, so we need to isolate it:
x = ($7.00 - $0.31*y)/$0.15
Where x and y must be two whole numbers (notice that the value of x depends of the value of y).
Now you can try to evaluate in different whole values of y, such that the outcome (x in this case) is also a whole number.
The first value of y such that x is also a whole number is y = 10.
x = ($7.00 - $0.31*10)/$0.15 = 26
Then we conclude that she will get 26 of the 15-cent stamps.
If you want to learn more about linear equations:
brainly.com/question/1884491
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