What is the sum of the first 20 terms of the arithmetic sequence 3, 7, 11, ........?
A rectangle's length is twice its breadth. If the perimeter is 60 cm, what is its area?
In how many ways can 5 identical balls be distributed into 3 distinct boxes?
The roots of the quadratic equation $x^2 - 6x + k = 0$ are real and distinct. How many integer values of $k$ are possible if $k$ is positive?
A shopkeeper sells an item at a 20% discount but still makes a 20% profit. If the cost price is Rs. 100, what is the marked price?
If the sum of two numbers is 15 and their product is 56, what is the sum of their reciprocals?
A circle is inscribed in an equilateral triangle with side length 12 cm. What is the radius of the circle?
A and B can complete a task in 12 days, B and C in 15 days, and A and C in 20 days. How many days will A alone take?
If $3x + 4y = 12$ and $x - y = 1$, what is the value of $x + y$?