Question 291595
c=3
x+y=1 2/3
(b+c)*x=(b-c)*y
(b+c)=5/3*(b-c)
b = 12,   c = 3,   x = 1,   y = 5/3
boat 12
downstream 15
upstream 9
5/3=15/9
15*1=15 miles from a to b
check
9*5/3=15 
ok