Jill drove the 200 miles to Cincinnati at an average speed of 10 miles per hour faster than her usual average speed. If she completed the trip in 1 hour less than usual, what is her usual driving speed, in miles per hour
+36916 Normal speed = x
xt = 200 t = 200/x
faster speed (x+10 ) new time = t-1 = 200/x -1
(x+10)(200/x -1) = 200 miles
200 -x + 2000/x -10 = 200
-x + 2000/x -10 = 0
-x^2 + 2000 - 10 x = 0 via quadratic formula x = 40 m/hr
