Twice the difference between two numbers is equal to their sum. If one number is 15, find the other number.

If a cuboid of dimensions 64cm×16cm×8cm is melted and recast into two equal cubes of same size. Then what will be the ratio of the surface are of cuboid to the total surface area of the two cubes?

Three solid metallic sphere whose radii are 3cm, x cm and 18cm respectively, are melted and recast into a single solid sphere of diameter 38cm. Then find the total surface area of the sphere with radius x cm?

If the right prism having trapezium base, whose parallel side are 13cm and 15cm respectively and the distance between them is 12cm. If the volume of the prism is 2150.4cm^z, then find the height of the prism.

Vaishnavi and Saurabh start moving at the same time from city A to city B, 60 km away. Vaishnavi travels 4 km/hr slower than Saurabh. Saurabh reaches city B and at once turns back meeting Vaishnavi, 12 km from city B. What is the speed of Vaishnavi ?

Ram does a work in 40 days and Shyam does same work in 60 days. If efficiency of Mohan is 20% less than the combined efficiency of Ram and Shyam together then working alone Mohan will complete the whole work in how many days?

A train travelling at a constant speed crosses a pole in 12 seconds whereas cross a tunnel 198 metre long in 30 seconds. Find the length of train.

A is inversely proportional to square of B whereas directly proportional to C. Value of A was 27 when value of B was 4 and value of C was 6. Find the value of A when value of B will be 3 and value of C will be 8.