Explanation:

- Let the number of products sold by B in 2015 be \( x \).

- Then the number of products sold by A in 2015 is \( 1.5x \).

- In 2017, A sold \( 1.5x + 14 \) products.

- A in 2016 sold 10% less than in 2017, which is \( 0.9 \times (1.5x + 14) \).

- The number of products sold by B in 2017 is \((8/3)x \).

- Total products sold by B in all three years is: \( x + (x + 1) + \frac{8}{3}x = \frac{14}{3}x + 1 \).

- This is 1 less than the total sold by A and B in 2017, so \( \frac{14}{3}x + 1 = (1.5x + 14) + \frac{8}{3}x - 1 \).

- Solving gives \( x = 15 \).

- Unsold products by A in 2017: \( 0.6 \times (1.5 \times 15 + 14) = 16.8 \).

- Unsold products by B in 2017: \( 0.36 \times (\frac{8}{3} \times 15) = 55.2 \).

- Difference: \( 55.2 - 16.8 = 38.4 \) (rounded to 39).