Answer:
The speed of wind is 75 miles / hour
Explanation:
Let's assume
speed of airplane is x miles /hour
speed of wind is y miles /hour
Against wind:
An airplane travels 600 miles against the wind in 4 hours
against wind means resultant speed will be less
so, speed =x-y
total distance traveled in 4 hour is
![=4(x-y)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/9we6b65wadovn0low6xaovpnlmeg50z54k.png)
and this has to be equal to 600
![600=4(x-y)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/allej4nfozv352f44stpn2txnis1b0z2oc.png)
Divide both sides by 4
and we get
![x-y=150](https://img.qammunity.org/2019/formulas/mathematics/middle-school/nmgodz1ed7k69pnmzmdsfsakj1zpz5534e.png)
With wind:
makes the return trip with then same wind in 2 hours
with wind means resultant speed will be more
so, speed =x+y
total distance traveled in 2 hour is
![=2(x+y)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/3wzoekp7arcsdenm7hqozuk160l03uome8.png)
and this has to be equal to 600
![600=2(x+y)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/2ayu6hra8uv8g25y24tdrl6gset7hkv88l.png)
Divide both sides by 2
and we get
![x+y=300](https://img.qammunity.org/2019/formulas/mathematics/middle-school/6ltcovxvqiejr6pp7av8gi66m5vqss2jx4.png)
So, we get system of equations
![x-y=150](https://img.qammunity.org/2019/formulas/mathematics/middle-school/nmgodz1ed7k69pnmzmdsfsakj1zpz5534e.png)
![x+y=300](https://img.qammunity.org/2019/formulas/mathematics/middle-school/6ltcovxvqiejr6pp7av8gi66m5vqss2jx4.png)
now, we can solve it by adding both equations
![x-y+x+y=150+300](https://img.qammunity.org/2019/formulas/mathematics/middle-school/zxukeqv6mss7am1vbbx3rdeesc5cxmiwms.png)
![2x=450](https://img.qammunity.org/2019/formulas/mathematics/middle-school/27nhgajqjaf13v1pza4snqndovk60ayhmp.png)
now, we can solve for x
![x=225](https://img.qammunity.org/2019/formulas/sat/high-school/5889rs3s7mx85ym0tyexr818va37ykfbda.png)
now, we can find y by plugging x into any one equation
![225+y=300](https://img.qammunity.org/2019/formulas/mathematics/middle-school/f4uwn0vps2sv8gf541vqhgkq9yru4v4zfd.png)
![y=75](https://img.qammunity.org/2019/formulas/mathematics/middle-school/3dxnjn0unaf0jf2amvkijqv22afb8p7n3q.png)
So,
The speed of wind is 75 miles / hour