'X' sells fruits at 21% profit. If X bought it for 9% less and sold it for Rs.29 less, he would have gained 25%. The cost price of fruits is?

Let the cost price of the fruits be 'C.P'

From the given data, after analysis it can be solved as

(121% of C.P) - (125% of 91% of C.P) = 29

$$\begin{gathered} 121 100 C . P - 125 100 x 91 100 x C . P = 29 \\ 121 100 - 125 x 91 100 x 100 C . P = 29 \\ ( 12100 - 125 x 91 ) C . P = 290000 \\ ( 12100 - 11375 ) C . P = 290000 \\ 725 C . P = 290000 \\ C . P = 400 \end{gathered}$$

Hence, the cost price of the fruits = Rs. 400.