A function is written in slope intercept form (y = mx + b)
so we first have to find the y-intercept or "b" in the question it states that they started off 400 miles away so that would be the "b" then you would need to find the m or slope and in the question it says after seven hours they where 50 miles away and 400 minus 50 is 350 so they traveled 350 miles in 7 hours so you then have to divide 350 by 7 and you get the slope 50 but since it is to find out how far away they are we make it negative giving you the equation y = -50 +400. Hope you found this helpful :D
