document.write( "Question 98923: Two planes are 2100 miles apart and traveling towards each other. One plane is traveling 80 mi/hr. faster than the other plane. The planes meet in 2.5 hr. Find the speed of the slower plane. \n" ); document.write( "
Algebra.Com's Answer #72008 by Adam(64)\"\" \"About 
You can put this solution on YOUR website!
This is the variation of problem I was already solving. So look at problem 73154 for some info. Anyway, crucial idea - times of flight of both planes are same -) t1=t2 s = v/t v*t=s\r
\n" ); document.write( "\n" ); document.write( "v1 = x
\n" ); document.write( "v2 = x+80\r
\n" ); document.write( "\n" ); document.write( "this is what we substitute into our equations\r
\n" ); document.write( "\n" ); document.write( "v1*t=s1
\n" ); document.write( "v2*t=s2
\n" ); document.write( "s1+s2 = 2100\r
\n" ); document.write( "\n" ); document.write( "and get:\r
\n" ); document.write( "\n" ); document.write( "x*t=s1
\n" ); document.write( "(x+80)t = s2
\n" ); document.write( "s1+s2 = 2100\r
\n" ); document.write( "\n" ); document.write( "x*t+(x+80)*t = 2100
\n" ); document.write( "x*t+x*t+80t = 2100
\n" ); document.write( "2xt=2100-80t
\n" ); document.write( "2x= (2100-80t)/t
\n" ); document.write( "x = (2100-80t)/2t
\n" ); document.write( "- (analytic solution)
\n" ); document.write( "-
\n" ); document.write( "x= (2100-80*2.5)/5
\n" ); document.write( "x= (2100-200)/5
\n" ); document.write( "x= 1900/5
\n" ); document.write( "x= 380 miles/hour\r
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