What is the difference between number of laptops (both Dell and Lenovo) sold by store Q and total number of Lenovo laptops sold by store R and S together?

Answer: Option B

Percent of Laptops Dell and Lenovo sold by store Q = 23%
Number of Laptops Dell and Lenovo sold by store Q
$$\begin{array}{rl}& =4500\times \frac{23}{100}\\ & =45\times 23\\ & =1035\end{array}$$
Percent of Laptops Dell and Lenovo sold by R and S together
  = 35% + 11%
  = 46%
Now, total number of Laptops Lenovo and Dell sold by R and S together
$$\begin{array}{rl}& =4500\times \frac{46}{100}\\ & =2070\end{array}$$
Percent of Dell Laptops sold by R and S together
  = 30% + 9%
  = 39%
Number of Dell Laptops sold by R and S together
$$\begin{array}{rl}& =2400\times \frac{39}{100}\\ & =936\end{array}$$
Number of Lenovo Laptops = 2070 - 936 = 1134
Required difference
  = 1134 - 1035
  = 99