Answer:
20,000 pairs of barber scissors.
Step-by-step explanation:
The sales volume <em>V</em> for barber scissors is directly proportional to the size <em>S</em> of the sales force and inversely proportional to the price <em>P</em> of the scissors.
In other words, we can write that:

Where <em>k</em> is the constant of proportionality.
19,440 pairs were sold in 2013, when there was 54 salespeople and the price was $20 a pair. Hence, <em>V</em> = 19440 when <em>S</em> = 54 and <em>P</em> = 20. Substitute and determine the value of <em>k: </em>

Hence, our equation is:

We want to determine the sales forecast with 50 salespeople and a price of $18 a pair. Hence, <em>S</em> = 50 and <em>P</em> = 18:

In conclusion, 20,000 pairs of barber scissors can be expected to be sold.