An ice-cream vendor is taking continuous rounds of a residential colony on a tricycle cart. He passes Gautam's house after every 30 minutes. A fruit seller walking with his cart takes rounds on the same path and passes Gautam's house in every 50 minutes. If Gautam buys ice-creams and fruits from both of them together and the two start from his house at the same time, after how many minutes again will they pass simultaneously toghether in-front of Gautam's house.