Pump A can fill a tank in 36 minutes, while pump B can fill the same tank in 45 minutes. Both pumps are turned on together to fill the empty tank, but when tank became half full, pump B stops working and rest of the tank is filled by pump A only. How long it took to fill the tank?
A shopkeeper sells two qualities of coffee at the rates of €60 per kg. and €44 per kg, gaining 20% and 10% profit respectively. If he mixes the two variants in the ratio 4:1 and sells the mixture at €36 per kg., what is his gain or loss?