I think I got this one. haude_ko_bhai I got solution from your solution. you assumed that the second thread would burn in 15 mins, I dont know how you got that one coz it should take 1 hour for both. here is how you do it. Take two ends of thread one and one end of thread 2 and light them up. the moment thread one ends burning indicates the half hour mark. The second end of thread two should be burnt at the instance the thread one ends burning. Which means that half an hour of thread two is burnt. Thus half an hour of thread 2 should burn at instance thread one stops burning. Thus we get fourty five minutes. Thread one burns for 30 mins. Thread tow burns of 30 mins. The remaining of thread 2 equals 30 mins. When we burn both ends of thread 2 at that moment, thread 2 should burn for 15 mins. 30+15=45 mins. Man it took almost half an hour for that. Good one though Guest4