At $24\%$ discount, the selling price of a washing machine is $\text{Rs }38000$. What is the selling price if the discount is $40\%$?

Let the Marked Price (MP) of the washing machine be $100\%$.When a discount of $24\%$ is offered, the selling price is:
$${\text{SP}}_1=100\%-24\%=76\%\text{ of MP}$$
Given that ${\text{SP}}_1=\text{Rs }38000$:
$$76\%\text{ of MP}=38000$$
$$\text{MP}=\frac{38000}{76}\times 100=500\times 100=\text{Rs }50000$$
When the discount is altered to $40\%$, the new selling price is:
$${\text{SP}}_2=100\%-40\%=60\%\text{ of MP}$$
$${\text{SP}}_2=\frac{60}{100}\times 50000=60\times 500=\text{Rs }30000$$