The horizontal distance between the two balloons is 53.8 meters.
<u><em>Explanation</em></u>
According to the below diagram, A and B are the positions of two balloons which are 48.2 meter and 61.0 meter above the ground respectively.
Horizontal distance between two balloons is AC, which is
meter.
A person in the left balloon observes that the right balloon is 13.38° above the horizontal. That means, ∠BAC = 13.38°
According to the diagram, 
Now in right angle triangle ABC.....

So, the horizontal distance between the two balloons is 53.8 meters.