the merging of two streams to form a river. One stream has a width of 8.9 m, depth of 3.5 m, and current speed of 2.1 m/s. The other stream is 6.5 m wide and 3.7 m deep, and flows at 2.2 m/s. The width of the river is 10.7 m, and the current speed is 3.1 m/s. What is its depth?