Shauna gets on a train 10 miles north of Washington, D. C. 45 minutes later she is 40 miles south of Washington, D. C. The train was moving at
a constant rate. Let Washington, D. C. be a location of zero, North be
positive, and South be negative. The equation for this situation is
1 = at + b, where is location in miles and tis time in minutes. Choose
the correct a and b for this equation.