ABC is an isosceles triangle with AB = AC. The side BA is produced to D such that AB = AD. If ∠ABC = 30°, then ∠BCD is equal to 

A sum of money doubles itself at compound interest in 15 years. In how many years it  will become eight times?

What is the value of 300°?

If a shopkeeper increases the selling price of an article by 10% and gets a profit of 37.5% on its cost price. If he increases the selling price by 25% above on old selling price then he gets a profit of ₹ 225 on his cost price. Find the cost price of the article?

$$ ({2+\sqrt{5}})$$ and $$ ({2-\sqrt{5}})$$ is a quadratic equation with roots.

What will be come in place of question mark(?) in the following number series?
8,  14, 25, 46, 82 , ?

A container in the shape of a frustum of a cone having diameters of its two circular faces as 35 cm. and 30 cm and vertical height 14 cm. is completely filled with oil. If each cm3 of oil has mass 1.2g, then find the cost of oil in the container if its costs Rs. 40 per kg.

The distance between the centers of two circles having radii 4.5 cm. and 3.5 cm. respectively is 10 cm. What is the length of the transverse common tangent of these circles?