The graph models the height h, in meters, of a hot air balloon, t minutes after beginning to
descend. How high was the balloon when it
began its descent?

The balloon was _ m high when it began its descent

The greatest height of the Ballon whn it began it's descent is given by the intercept value of the graph. Hence, the height of Ballon when it began it's descent is 80 meters.

The slope of the graph is negative signifying that the value on the y-axis decreases as the value on the x - axis increases.

The y - intercept is the value of y when x=0. This value represents the height at time = 0; when descent is about to begin. Hence, the ballon was 80 meters high.

Learn more : link