If 3x+0.04x=0.608, find x. 

If the annual rate of simple interest increases from 8% to 13%, a man’s yearly income increases by Rs. 4800. His principal (in Rs.) is:   

A vacuum cleaner was marked at 30% above the cost price and a discount of 24% was given on its marked price. What is the profit/loss percentage?

Ganesh, Shankar and Sameer invested Rs. 4200, Rs. 8400 and 5400 respectively while starting a business. At the end of the year, they earned a profit of Rs. 24,000. Sameer invested 32% of. his share of the profit in a saving scheme. How much amount he is left with?

Oranges are bought at 7 for Rs. 3. At what rate per hundred must they be sold to gain 33 % ? 

Two train of length 100 meter and 80 meter respectively run on parallel lines of rails. When running in the same direction the faster train passed the slower one in 18 second, but when they are running in opposite directions with the same speed as earlier, they pass each other  in 9 seconds. Find the speed of each train.

If 3 toys are sold at the cost price of 4 toys of the same kind, the profit will be:

A solid metallic sphere of radius x cm is melted and then drawn into 126 cones each of radius 3.5 cm and height 3 cm. There is no wastage of material in this process. What is the value of x?