Answer:
current rate = c = 5* [tex]\sqrt{3}[/tex] mph = 8.66 mph
Step-by-step explanation:
it looks like we do not know 2 things
the rate against the current and the rate with the current.
let c = rate of current
15 mph = rate of the two sailors.
15 + c = rate with current
c - 15 = rate against current
total time travel = 20 hours
(15 + c)*a = 200
(15 - c)*b = 200
a + b = 20
b = 20 - a
Let us read this right, I think the total trip is 400 miles
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(15 - c)*(20 - a) + (15 + c)*a = 400
300 - 20c -15a + ac + 15a + ac = 400
300 - 20c + 2ac = 400
100 = -20c + 2ac
50 = 10c - ac
50 = c*(a - 10)
c = 50/(a - 10)
assuming (15 + c)*a = (15 - c)*b
(15 + c)*a = (15 - c)*(20 - a)
15a + ac = 300 + ac - 20c - 15a
30a = 300 + 20c
a = 10 + (2/3)c
c = (3/2)*(a - 10)
(3/2)*(a - 10) = c = 50/(a - 10)
(a - 10)^2 = 100/3
a = 10 + root(100/3)
b = 20 - a = 10 - root(100/3)
c = 50/(a - 10) = 50 / (10 + root(100/3) - 10) = 50/ root(100/3)
c = 50 / ( 10/ root(3)) = 5 root(3) =
