Answer: The number of pen purchased by Diane is 7.
Step-by-step explanation: Given that Joe’s department store sells pens for 60 cents each and pencils for 40 cents each.
Diane purchased a total of 17 items for $8.20.
We are to find the number of pen that Diane purchased.
We know that
1 cent = $ 0.01.
Let x and y represents the number of pen and pencils that Diane purchased.
Then, according to the given information, we have

and

Substituting the value of y from equation (ii) in equation (i), we get

Thus, the number of pen purchased by Diane is 7.