For which value of k does the pair of equations x²-y²=0 and (x-k)²+y²=1 yield a unique positive solution of x?√

Two persons A and B start walking simultanoeusly from two places c km apart and walk in the same direction.If A travels at the rate of p km/hr and B travels at the rate of q km/hr ,then A has travelled before he overtakes B at a distance of

A car travels the first one-third of a distance with a speed of 10km/hr,the next one-third distancewith a speed of 20km/hr and the last one-third distance with a  speed of 60km/hr.The average speed of the car for the whole journey is

A man rows 32km downstream and 14km upstream and he takes 6 hours to cover each distance.What is the speed of current?

In how much time the SI on  a principal amount be 0.125 times principal amount  at 10% p.a?

A person could save 10% of his income.But 2 years later,when his income increased by 20%,he could save the same amount only as before.By how much percentage has  his expenditure increased?