Question 908577
Assign variables and make a data table.
Uniform Rates rule is RT=D for rate, time, distance.


r, speed of plane if no wind
d, distance of trip each way
20, speed of tailwind, mph miles per hour



______________________speed__________time__________distance
WITH__________________r+20___________4_____________{{{d=(r+20)*4}}}
AGAINST_______________r-20___________5_____________{{{d=(r-20)*5}}}


The same distance d for the trip WITH the wind and AGAINST the wind.
Clear enough.  You should see to form one equation in one unknown variable.