Profit and Loss...

What is the S.P. of a dozen of roses, if the C.P. of each rose is Rs. 1.20 and the profit on selling 30 roses is Rs. 5.40?

Ravi purchased a Book for Rs. 300 and sold it to Ramesh at a gain of 25%. Ramesh sold it to Rajendra at a loss of 10%. For how much did Rajendra buy it?

By selling an article for Rs. 600, a man gains 20% on the C.P. At what % should he sell it to gain 30%?

A watch is sold for Rs. 350. If sales tax accounts for one-tenth of this and profit is one-fifth of the remainder, find the C.P. of the watch.

On selling a tape recorder for Rs. 3600, Suresh loses 10%. Calculate his loss or gain % if he sells it for Rs. 4225.