document.write( "Question 220651: A bicyclist traveled 280 km at a certain speed. If the speed had been increased by 5 km/h, the trip could have been made in 1 hour less time. Find the actual speed?
\n" ); document.write( "I have tried d= r(t) with d=280 and r= x and r=x+5 with time being constant so that 280/x-280/x+5=1. I think I am on the right track , but do not have it quite right. Thanks. \n" ); document.write( "
Algebra.Com's Answer #165589 by nerdybill(7384)\"\" \"About 
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A bicyclist traveled 280 km at a certain speed. If the speed had been increased by 5 km/h, the trip could have been made in 1 hour less time. Find the actual speed?
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\n" ); document.write( "You indeed start with:
\n" ); document.write( "d = rt
\n" ); document.write( "But, in this case, we are talking about time. Solve the above equation for 't':
\n" ); document.write( "t = d/r
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\n" ); document.write( "Let x = actual speed
\n" ); document.write( "then
\n" ); document.write( "280/x = 280/(x+5) + 1
\n" ); document.write( "Multiply both sides by x(x+5)
\n" ); document.write( "280(x+5) = 280x + x(x+5)
\n" ); document.write( "280x+1400 = 280x + x^2+5x
\n" ); document.write( "1400 = x^2+5x
\n" ); document.write( "0 = x^2+5x-1400
\n" ); document.write( "Factoring:
\n" ); document.write( "0 = (x-35)(x+40)
\n" ); document.write( "x = {35, -40}
\n" ); document.write( "Since the negative solution doesn't make sense, throw it out -- leaving:
\n" ); document.write( "x = 35 km per hour\r
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