16 men can complete a piece of work in 7 days. In how many days will 28 men complete the same work?

Some amount out of Rs.7000 was lent at 6% per annum and the remaining at 4% per annum. If the total simple interest from both the fractions in 5 year was Rs.1600, find the sum lent at 6% per annum.

What are the roots of the quadratic equations?

  $$(x^2 + 3x - 154 = 0)$$

Suresh is half his father’s age. After 20 years, his father’s age will be one and a half times Suresh’s age. What is his father’s age now?

What will come in place of the question mark (?) in each of the following series?

3 22 ? 673 2696 8093 

A trader bought 10 kg of apples for Rs. 405 out of which 1 kg of apples were found to be rotten. If he wishes to make a profit of 10 % at what rate should he sell the remaining apples per kg? 

If $$ {3^{4x-y}={3^{x+y}=\sqrt{27}}}$$,  then the value of y is: