A sells an article which costs him Rs. 400 to B at a profit of 20%. B then sells it to C, making a profit of 10% on the price he paid to A. How much does C pay B ?

\par C.P. of B = 120\% of Rs. 400 = Rs. \left(\frac{120}{100}\times 400)\right) = \par Rs. 480

\par C.P. for C = 110\% of Rs. 480 = Rs.\left(\frac{110}{100}\times 480) \right)= \par Rs. 528