arithmetic - a boatman travelling with a speed of 10 kmph in standing water he can travel downstream 20 kms in the same time as he can travel 12 kms upstream find the speed of the current - skillgun

Let the speed of the current be ‘x’ kmph
Speed = distance / time
Time = distance / speed
20 / (10 + x ) = 12 / (10 - x)
20 (10 - x) = 12 (10 + x);
x = 2.5 kmph