Answer:
Speed of airplane in still air = 630 mile per hour
Speed of wind = 70 miles per hour.
Step-by-step explanation:
Let speed of plane in still air =
miles/hour
Let speed of wind =
miles/hour
Speed of airplane with the wind can be given by =
miles/hour
Speed of airplane against the wind can be given by =
miles/hour
Distance of the trip = 2800 miles
Time taken by airplane to travel with the wind = 4 hours
Speed of plane with wind =
![(Distance)/(Time)=(2800)/(4)=700\ miles/hour](https://img.qammunity.org/2020/formulas/mathematics/middle-school/biby06zkemccxram3kiqyqooe07xsjo960.png)
Distance of the return trip (same trip distance) = 2800 miles
Time taken by airplane to travel with the wind = 5 hours
Speed of plane with wind =
![(Distance)/(Time)=(2800)/(5)=560\ miles/hour](https://img.qammunity.org/2020/formulas/mathematics/middle-school/r735fre8dqb2xmqaycubwyh1n15sokgikm.png)
So, we have the system of equations:
A)
![x+y=700](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8ysxymktwl093byplo3m8sox43w954lgco.png)
B)
![x-y=560](https://img.qammunity.org/2020/formulas/mathematics/middle-school/7g5fksk4tdnq4yp2c1288kb5jsvzkbg0e4.png)
Using elimination method to solve.
Adding equation A to B to eliminate
.
![x+y=700](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8ysxymktwl093byplo3m8sox43w954lgco.png)
+
![x-y=560](https://img.qammunity.org/2020/formulas/mathematics/middle-school/7g5fksk4tdnq4yp2c1288kb5jsvzkbg0e4.png)
We get
![2x=1260](https://img.qammunity.org/2020/formulas/mathematics/middle-school/jlfbqk35833xnjzsm7ygewuhtn6ytep656.png)
Dividing both sides by 2.
![(2x)/(2)=(1260)/(2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/htgc5oqyo5hw90dkt2fl5wmg10lweozxhh.png)
∴
![x=630](https://img.qammunity.org/2020/formulas/mathematics/middle-school/vsv45o85c5hfqqqr4pg5cy83ogi3n9gosv.png)
Using
in equation A to find
![y](https://img.qammunity.org/2020/formulas/mathematics/college/uw0b7dbqmfpakodpw1nh8u5h9nrcutx8vw.png)
![630+y=700](https://img.qammunity.org/2020/formulas/mathematics/middle-school/6kugg3729a2zh2yyu9lixd0idjgcmarczu.png)
Subtracting both sides by 630
![630+y-630=700-630](https://img.qammunity.org/2020/formulas/mathematics/middle-school/esyfzacly4jtx8n2b43dd3wrpznwb6gqxg.png)
∴
Speed of airplane in still air = 630 mile per hour
Speed of wind = 70 miles per hour.