Number of Dell laptops sold by store Q is approximately what percent of the number of the number of laptops (both Dell and Lenovo) sold by store R?

Answer: Option D

Percent of Dell Laptops sold by store Q = 25%
Total number of Dell Laptops bold by store Q
$$\begin{array}{rl}& =2400\times \frac{25}{100}\\ & =600\end{array}$$
Percent of Laptops Dell and Lenovo sold by store R = 35%
Number of Laptops Dell and Lenovo sold by store R
$$\begin{array}{rl}& =4500\times \frac{35}{100}\\ & =1575\\ & \therefore \text{Required Percentage}\\ & =\frac{600}{1575}\times 100\\ & =38.095\\ & \approx 38\%\end{array}$$