Suppose the toll is $10. Then, .04m + 1.26 = 10. We can simplify that to .04m = 8.74 and again to m =218.5. Now, suppose the toll is $11. Then, .04m + 1.26 = 11. Going through the same steps as before we find that m = 243.5. So a $10 fair will allow a passenger to travel 218.5 miles while an $11 fare will allow 243.5 miles of travel. The difference between these two is 25 miles. Since the fares are $1 apart, that means each additional $1 increase results in 25 additional miles.
More simply, 0.04m gives the slope of the line telling us how many miles are traveled per dollar of fare, which is to say 0.04. So we could divide 1 by .04 to get the same result.
