Answer
The total elevation dropped by $-\frac{7}{10}$ ft.
Work Step by Step
Write the question as a numerical expression for the changes in elevation, and add from left to right.
$-\frac{2}{5} + \frac{9}{10} + (-\frac{6}{5})$
= $-\frac{4}{10} + \frac{9}{10} + (-\frac{12}{10})$
= $\frac{5}{10} + (-\frac{12}{10})$
= $-\frac{7}{10}$
