To determine Sasha's elevation after she descends to the fourth rest station, we can follow these steps:
1. Identify the distance between rest stations: Each rest station is [tex]$\frac{2}{3}$[/tex] of a mile apart.
2. Calculate the total descent distance for four rest stations: Since she descends to the fourth rest station, the total distance she has descended is the distance between rest stations multiplied by the number of rest stations.
[tex]\[
\text{Total distance descended} = 4 \times \frac{2}{3} \text{ miles}
\][/tex]
3. Perform the multiplication:
[tex]\[
4 \times \frac{2}{3} = \frac{8}{3} \text{ miles}
\][/tex]
4. Convert to decimal form for easier interpretation:
[tex]\[
\frac{8}{3} \approx 2.6667 \text{ miles}
\][/tex]
5. Determine Sasha's elevation after the descent: Since she started at sea level (which we consider as 0 elevation), descending 2.6667 miles means her current elevation is below sea level by that amount. Hence, her elevation is:
[tex]\[
0 - 2.6667 = -2.6667 \text{ miles}
\][/tex]
Thus, Sasha's current elevation after descending to the fourth rest station is approximately [tex]\(-2.6667\)[/tex] miles.
