When a linear equation is in the form y = mx + c, the c, or constant, is the intercept on the y axis, meaning it crosses the y axis at (0, 1).
The gradient (1/3 in this case) is how much the y increments (or decrements) per increase of 1 of the value of x.
This would mean that there would be one point at (0, 1), and another at (3, 2). Draw a line from these two points and beyond, and that is the graph sketched.
The anser is 11 you can see
Given that the tornado traveled 260 miles in 4 hours, its initial speed is 65 mi/h. Then, slowing by 20% every hour, the speed after 2 hours can be calculated through the equation,
speed = (65 mi/h) x (1-0.2)^2
speed = 41.6 mi/h
Thus, the speed of the tornado after 2 hours is approximately 41.6 mi/h.