77) The ratio between the present ages of Ravi and Jai is 3:2. If Ravi was 6 years older than Jai, four years back, how old is Jai now?

78) By selling a tape-recorder for 950, I lose 5%. What percent shall I gain by selling it for a 1040?

79) When 1 is added to each of the given two numbers, their ratio becomes 3 : 4 and when 5 is subtracted from each, the ratio becomes 7 : 10. The numbers are

80) 5 men or 9 women can do a piece of work 19 days. In how many days will 3 men and 6 women working together will finish the work?

81) Two pipes can fill a tank in 20 minutes will 30 minutes respectively. If both the pipes are opened simultaneously, then the tank will be filled in