Velocity of that jet flying against the jetstream is:
[tex]V_1=\frac{3950}{5}=790\text{ miles/hour}[/tex]
And the velocity of that jet flying with the jetstream is:
[tex]V_2=\frac{10170}{9}=1130\text{ miles/hour}[/tex]
Let the velocity of that jet in still air be x miles per hour and the velocity of jetstream be y miles per hour, so:
[tex]x-y=790[/tex]
and
[tex]x+y=1130[/tex]
Adding the two equations we have:
[tex](x-y)+(x+y)=790+1130[/tex][tex]x-y+x+y=1920[/tex][tex]2x=1920[/tex][tex]x=\frac{1920}{2}[/tex][tex]x=960[/tex]
the velocity of that jet in still air is 960 miles per hour.
And the rate of the jetstream "y" is (replacing x in the first equation):
[tex]x-y=790[/tex][tex]960-y=790[/tex][tex]y=960-790[/tex][tex]y=170[/tex]
170 miles per hour
