Adding percents and figuring out a percent of a whole number is super easy. I'll show you how.
First, all we have to do is take the percent, and turn it into a decimal. For example, 10% would turn into 0.10, 25% would turn into 0.25. In this case, 47 percent turns into 0.47.
Now that we have the decimal for 47% (0.47), all we have to do is multiply it by the number we're adding to.
13,500 x 0.47 = 6345
Now, this step isn't required for the question, but for the sake of learning, we'll add 6345 to the original number, giving us the total after adding 47%.
13,500 + 6345 = 19845
There's your answer. The sales have increased by $6,345. The total was $19,845 (not your answer).
I hope this explanation helped you out. Let me know if there is any confusion. :)