Answer:
She purchased 4 pencils
Explanation:
Here, we are to calculate the number of pencils bought given the information in the question.
The amount per pencil is $0.91. The total amount of this since she bought x number of pencils is $0.91 * x = $0.91x
Now, after paying $10, she was given $6.36 as change
what this means is that what the pencils cost is 10-6.36 = $3.64
Now we equate the cost in terms of x to this;
0.91x = 3.64
x = 3.64/0.91
x = 4 pencils