Fort Lauerdaule,Fl is about 9 ft above sea level and New Orleans,LA is about 6 ft below sea level. What is the difference in their elevations?
9 --> 0 is down 9
and then down more
0 ---> -6 = down 6
total down = 15
and then down more
0 ---> -6 = down 6
total down = 15