[tex]\text{Calculate how far apart the balloon and submarine are from each other}\\\\\text{We know that the balloon is 100,000 feet ABOVE sea level}\\\\\text{We also know that the submarine is 15,840 BELOW sea level}\\\\\text{To find the distance between each other, add the values, since they're}\\\text{farther apart since one's below sea level and one is above sea level}\\\\100,000+15840=115,840\\\\\boxed{\text{Answer: 115,840 feet apart }}[/tex]
