Answer:
6 mph
Step-by-step explanation:
If x is the rate of boat (given x = 28)
and c is the rate of Gulf Stream (we need to find this)
The rate downstream is with the current, that is
x+c
THe rate of upstream is against the current, that is
x-c
We also know D = RT
D is distance
R is rate
T is time
It takes same time, so we can say:
t = D/R
So we can equate both to:
[tex]\frac{170}{x+c}=\frac{110}{x-c}\\\frac{170}{28+c}=\frac{110}{28-c}[/tex]
We can cross multiply this and solve for c:
[tex]\frac{170}{28+c}=\frac{110}{28-c}\\170(28-c)=110(28+c)\\4760-170c=3080+110c\\1680=280c\\c=6[/tex]
The speed of current (rate of Gulf Stream) = 6 miles per hour
