it takes car A to travel 400 miles 2 hours less than car B (same distance). if the avg of car A's speed was 10 miles per hour greater than that of car B, what was Car B's avg speed per mile?
…….Rate….Time….Distance
A…..R+10…..T-2…..400
B…..R……….T…….400
RT = RT +10T -2R – 20
2R + 20 = 10T
R+10 = 5T
(R+10)/5 = T
R(R+10)/5 = 400
R^2 + 10R = 2000
R^2 + 10R – 2000 = 0
(R + 50)(R – 40) = 0
R= -50 or R=40
R can’t be negative so R is 40.
