<PRE><B>Question 441538</B>
Write the equation of this problem: 
Suppose an airplane can travel 160 miles in the same time a second airplane can travel 200 miles.
 If the speed of the second airplane is 20 miles per hour faster than the first
 airplane, what was the speed of the first airplane?
:
Let s = speed of the 1st airplane
it says,&quot;the speed of the second airplane is 20 miles per hour faster than the first&quot; therefore:
(s+20) = speed of the 2nd airplane 
:
Write time equation; time = dist/speed
:
2nd plane travel time = 1st plane travel time
{{{200/((s+20))}}} = {{{160/s}}}
:
Cross multiply 
200s = 160(s+20)
200s = 160s + 3200
200s - 160s = 3200
40s = 3200
s = {{{3200/40}}}
s = 80 mph speed of 1st plane
then
80 + 20 = 100 mph speed of the the 2nd plane
;
:
Confirm this, find the actual times, they should be equal
200/100 = 2 hrs
160/80 = 2 hrs</PRE>