Annette drives her car 105 miles and has a mean of a certain speed. if the mean speed had been 4mph more, she could have traveled 119 miles in the same length of time. what was her mean speed?

Let the mean speed be x mi/hr

Time taken to travel will be:

distance / speed

thus:

105/x=119 / (x+4)

solving for x we get:

105 (x+4) = 119x

105x+420=119x

119x-105x=420

x=30 mi/hr

Thus the mean speed is 30 mi/hr