I got as far as plane speed + wind = 158 and plane speed - wind = 112.

But I don't know how to solve the problem.

I got as far as plane speed + wind = 158 and plane speed - wind = 112.

But I don't know how to solve the problem.

Tutors, sign in to answer this question.

John R. | John R: Math, Science, and History TeacherJohn R: Math, Science, and History Teach...

You need to name variables for plane speed and wind speed. For example, I will name them:

x = Plane speed

y = Wind speed

Now you can create two equations in two variables

x + y = 158

x - y =112

This is a good problem for elimination method since you already have one equation with positive y and the other with negative y

x + y = 158

x - y = 112

2x = 270

x = 135

Now substitute the value into either equation to solve for y

x + y - 158

135 + y = 158

y = 23

Already have an account? Log in

By signing up, I agree to Wyzant’s terms of use and privacy policy.

Or

To present the tutors that are the best fit for you, we’ll need your ZIP code.

Your Facebook email address is associated with a Wyzant tutor account. Please use a different email address to create a new student account.

Good news! It looks like you already have an account registered with the email address **you provided**.

It looks like this is your first time here. Welcome!

To present the tutors that are the best fit for you, we’ll need your ZIP code.

Please try again, our system had a problem processing your request.

## Comments

I used this method on another problem and I'm getting two different answers.

A small jet plane whose speed in still air is 220 km/h can travel 520 km with the wind in the same amount of time as it takes to fly 360 km against the wind. What is the wind speed?

I get (220+ 360)/2 = 70. But if I use John's method.

I get wind speed is 80.

220t +w = 520 and 220t -2 = 360. Using elimination method I get 440t =880

t=2. Then substitute into eq 1 and get 220(2) +w = 520 2 = 80

So which is right?

Wind speed is 40 km/h; total trip time 880 km/ 220 km/h= 4hours.

2 hours each leg==> 520/2= 260 km/h with 40 wind boost; 360/2= 180 km/h against same wind of 40 :)

Wind speed is 40 km/h; total trip time 880 km/ 220 km/h= 4hours.

2 hours each leg==> 520/2= 260 km/h with 40 wind boost; 360/2= 180 km/h against same wind of 40 :)