Write and solve an equation to find the number $n$ . Eight plus the quotient of a number and $3$ is $-2$ .

Martha is training for a duathlon, which includes biking and running. she knows that yesterday she covered a total distance of over 55.5 miles in more than than 4.5 hours of training. martha runs at a speed of 6 mph and bikes at a rate of 15.5 mph.