Final answer:
Geoff's canoeing distance after x hours is represented by the point-slope equation y - 18 = 3.5(x - 5), where x is the number of hours and y is the distance traveled.
Step-by-step explanation:
Geoff paddles his canoe at an average speed, which can be described by the equation y = mx + b, where y represents the total distance traveled, m represents the average speed, x represents the time in hours, and b represents the initial distance (which is zero in this case since Geoff starts from the starting point).
To find the equation in point-slope form for Geoff's canoeing activity, we can use the given information: Geoff's average speed is 3.5 miles per hour, and he had already traveled 18 miles after 5 hours.
Now, we can express the point-slope form equation as y - y1 = m(x - x1), where (x1, y1) is a point on the line. For this situation, we can use (5, 18) as our point. Plugging in the values we get:
y - 18 = 3.5(x - 5)
This equation can be used to determine the total distance y Geoff travels after x hours of canoeing.