Question 15263
This figure is a right triangle with the balloon at a height of x miles above Sara's house.  The base of the triangle represents the distance from Sara's house to where Sara is at her friend's house.  The angle from Sara's friend's house to the balloon is 15 degrees, so trigonometry is required.


tan 15 = x/2


Multiply both sides by 2:
2 tan 15 = x


Are calculators allowed here?  Be sure you are in degree mode! 
x = 2 tan 15 = .535898 . . .


In case you want that in feet, multiply by 5280 (don't round it off until AFTER you do the calculation!!)  

about 2830 feet.


R^2 at SCC