P sells a toy to Q at a profit of 40% and Q sells it to R at a profit of 10%. If R pays Rs 539 for the toy, then what was the cost price of toy for P?

Rs 350

Let the Cost price of the toy be 100 units,

If P sells it at profit of 40%, then selling price to Q is 140 units,

This becomes the cost price for Q when he sells it to R at profit of 10%,

Selling price for this transaction is $\frac{110}{100}$ x 140 = 154 units

But R pays Rs 539 for the toy, 

Using unitary method

If 154 units = Rs 539

⇒     1 unit  = Rs $\frac{539}{154}$

and 100 units = $\frac{539}{154}$ x 100 = Rs 350

Thus, the cost price of the toy is Rs 350