If pq+qr+rp=0 then find the value of $$ {p^{2}\over {p^{2}-qr}}+{q^{2}\over {q^{2}-rp}}+{r^{2}\over {r^{2}-pq}}$$

P purchase an item for Rs 1200 and sold it on a profit of 10%. If he sells it at Rs 1380 then calculate his increase in profit percentage. 

A sum of money is invested at 20 % compound interest (compounded annually). It would fetch 723 more if interest is compound half-yearly. The sum is –

What are the roots of the quadratic equations?

  $$(x^2 + 3x - 154 = 0)$$

Simplification the following equations

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?

In an examination, 30 percent of the students failed in English and 25 percent of the students failed in mathematics. If 15 percent of the candidates failed in both subjects, then what percentage of students passed in both subject.

The annual payment of Rs.1000 in  5 years at 4% per annum simple interest will discharge a debt of