The speed of the boat along the river is 19 km / h, and against the current 15 km / h.

| February 21, 2021 | education

The speed of the boat along the river is 19 km / h, and against the current 15 km / h. Find: a) The speed of the river flow b) the boat’s own speed.

Let x be the speed of the boat, and y the speed of the river. Since the speed of the boat along the river is 19 km / h, then x + y = 19, and the speed of the boat against the current is 15 km / h, then x – y = 15. We have a system of equations: x + y = 19, x – y = 15 .we express in the first equation the value of x through y: x = 19 – y, substitute in the second equation the value of x: 19 – y – y = 15, 19 – 15 = 2y, 4 = 2y, y = 4: 2, y = 2 The speed of the river is 2 km / h, then the speed of the river is: x = 19 – 2, x = 17 km / h. Answer: a) river speed – 2 km / h b) own speed of the boat – 17 km / h.



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