Water flows from the first reservoir to the second over a rectangular weir with a width-to-head ratio

Question:

Water flows from the first reservoir to the second over a rectangular weir with a width-to-head ratio of 3. The height P of the weir is twice the head. The water from the second reservoir flows over a 60° triangular weir to a third reservoir. Th e discharge across both weirs is the same. Find the ratio of the head on the rectangular weir to the head on the triangular weir.