Mathematics also occupies Fishing

Albert is fly fishing in a stream.The tip of fishing rod is 2.8 m. above the surface of water and the fly at the end of the string rests on water 3.6 m. away and 2.4 m. from a point directly under the tip of rod .Assuming that his string (from tip of his rod to the fly) is taut ,how much string does he have out? If she pulls in the string at the rate of 5 cm/sec.,what will be the horizontal distance of the fly from her after 12 seconds?Length of string will be 'n',and distance after 12 seconds be 'm' write your solution as $(m+n)^2$

Details and assumptions -Do not consider how fast the stream moves.