For a ship moving against the current, it takes 9 hours to cover a distance of 113.4 miles. how much does it take this ship to return if the rate of the current is 1.9 mph?

Let x mph be the speed of the ship in still water.
Against the current, the net speed is, (x-1.9) mph.
Time, t= distance, d/ Speed, v => 9= 113.4/(x-1.9) => 9(x-1.9) = 113.4 => x-1.9 = 113.4/9 => x = 12.6+1.9 = 14.5 mph

Moving with the current, the net speed of the ship = 14.5+1.9 =16.4 mph

Time take, t = d/v = 113.4/16.4 = 6.915 hours