.
Let u = the rate of the swift in calm air (mi/h), and
let v = the rate of the wind/
Then
= 140 = u + v is the effective tailwind speed, and
= 110 = u - v is the effective speed against the wind.
Adding the equation, you get
2u = 140 + 110 = 250 ====> u = = 125 mi/h the rate of the swift in calm air, and
v = 140-u = 140-125 = 15 mi/h for the rate of wind.
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.
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.