Question 26425
Let the speed of the plane be y
Let the speed of the wind be x
1 2/3 = 5/3
Against = -
With = +


2(x-y)=600 ------>2x-2y=600 (solve for y)
x-y=300
y=300+x (subsitution)


{{{(5(x+y))/3=600}}}---->{{{5x/3+5y/3=600}}} apply subsitution.
{{{5x/3+(5(300+x))/3=600}}}
{{{5x/3+(1500+5x)/3=600}}} ---> Remove the fraction by multipling the equation by 3.
{{{3(5x/3)+3((1500+5x)/3)=3(600/1)}}}
5x+1500+5x=1800
10x=300
x=30
y=300+(30)
y=330


Hence, the speed of the wind is 30 mph and the speed of the plane is 330 mph (in still air).
Paul.