Bala bought 3 pens and 2 files. The total cost of the 3 pens and 2 files was $7.65.

1. Calculate the change received by subtracting the total cost from the amount paid

$50 - 7.65 = 42.35$

1. Identify the relationship between the new quantities and the original quantities

Notice that $9$ pens and $6$ files is exactly $3$ times the original bundle of $3$ pens and $2$ files.

2. Calculate the total cost by multiplying the original cost by 3

$3 \times \char36{}7.65 = \char36{}22.95$