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Let u be the speed of the plane at no wind, and let v be the speed of the wind.
The effective speed with the wind
u + v = 1000/4 = 250 mph (1)
The effective speed against the wind
u - v = 1000/5 = 200 mph (2)
Add equations (1) and (2)
2u = 450
u = 450/2 = 225 mph
Next, from equation (1)
v = 250 - 225 = 25 mph.
ANSWER. The speed of the plane at no wind is 225 mph.
The speed of the wind is 25 mph.
Solved.
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It is a typical "tailwind and headwind" word problem.
See the lessons
- Wind and Current problems
- Wind and Current problems solvable by quadratic equations
- Selected problems from the archive on a plane flying with and against the wind
in this site, where you will find other similar solved problems with detailed explanations.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this textbook under the section "Word problems", the topic "Travel and Distance problems".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.