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

The sum of two numbers is 84 and their HCF is 12. Total number of such pairs of number is 

With a 5 % discount on the cost of sugar, a buyer could purchase 2 kg. more sugar for ₹ 608. Original selling price of sugar is. 

The printed price of a book is 320. A retailer pays 244.80 for it. He gets successive discounts of 10% and an another rate. His second rate is-

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? 

The average age of 30 boys in a class is 15 years. One boy, aged 20 years, left the class, but two new boys came in his place whose age differs by 5 years. If the average age of all the boys now in the class becomes 15 years, the age of the younger newcomer is: 

At present, the sum of the ages of A, B and C is 150 years, whereas 10 years ago, the ratio of their age was 5:4:3. Find the ratio of their ages 10 years hence.