Question 386063
time = distance / rate


[5 / (b - 4)] + [13 / (b + 4)] = 2


[5(b + 4)] + [13(b - 4)] = 2(b^2 - 16)


2b^2 - 32 - 5b - 20 - 13b + 52 = 0


b^2 - 9b = 0