Okay, let me first explain what the equation y = 8.77x + 686 means
y is the hikers elevation
Look at the graph and see what the y and x axis's are labeled as.
x is time.
8.77 is just the slop of the trend line.
686 is just the elevation the hiker starts at, or in technical terms, the y intercept. Y intercept is just where the lines touches the y axis.
The question asks what will be the hiker's elevation at 145 minutes.
To solve, just simply plug in 145 as X in the equation above. Remember x is time.
It will look like this :
y = 8.77 (145) + 686
Then solve.
y = 1271.65 + 686
y = 1957.65
Reminder: They want the nearest whole number!
Round 1957.65 feet to 1958 feet
Hope I helped! Message me if you have questions