Sachin alone can complete a piece of work for Rs. 8,500 in \(8\frac{1}{2}\) days. But with the help of Vishnu, the work is completed in 6 days. The share to be paid to Vishnu is:
A vertical post 15 ft. high is broken at a certain height and its upper part, not completely separated meets the ground at an angle of 30°. Find the height at which the post is broken