2. Formulate the following problems as a pair of equations, and hence find their solutions: (1) Ritu can row downstream 20 km in 2 hours, and upstream 4 km in 2 hours. Find her speed of rowing in still water and the speed of the current.​

Speed of water while upstream is (x + y) km/hr,

downstream is (x – y) km/hr,

2(x + y) = 20 x + y = 10 ………… (i)

2(x – y) = 4 x – y = 2 …………… (ii)

x + y = 10

x - y = 2

_______________

x = 12

(ii), Substituting the value,

(i), x + y = 10 6 + y = 10 y = 10 – 6

∴ y = 4

∴ Speed of Ritu in still water, x = 6 km/hr. in current water, y = 4 km/hr.