Answer :
L-83 ≤ L ≤ L + 83.7
Explanation:
Let the initial height of the balloon is L .
The lower level is L - 83 , because it goes 83 m downwards
The upper limit is L + 83.7 , because it goes up by 83.7 m
Thus the inequality becomes
L-83 ≤ L ≤ L + 83.7