document.write( "Question 426496: I can't come up with a suitable formula to solve this question please help.
\n" ); document.write( "In a certain number of hours, a woman travelled 36km. If she had travelled 1.5 km/h faster, it would have taken 3 hrs less to make the journey. how many kilometers did she travel per hour. \n" ); document.write( "
Algebra.Com's Answer #296690 by htmentor(1343)\"\" \"About 
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Let t = number of hours to travel the 36 km
\n" ); document.write( "Let s = the speed to travel the 36 km
\n" ); document.write( "So s = 36/t
\n" ); document.write( "We can represent 1.5 km/h faster as: s + 1.5
\n" ); document.write( "And 3 hrs less as t - 3
\n" ); document.write( "So we need to solve
\n" ); document.write( "s + 1.5 = 36/(t - 3)
\n" ); document.write( "Using the value for s above we can write
\n" ); document.write( "36/t + 1.5 = 36/(t - 3)
\n" ); document.write( "Multiply through by t:
\n" ); document.write( "36 + 1.5t = 36t/(t - 3)
\n" ); document.write( "Now multiply both sides by t - 3:
\n" ); document.write( "(t - 3)(36 + 1.5t) = 36t
\n" ); document.write( "Solve for t:
\n" ); document.write( "36t + 1.5t^2 - 108 - 4.5t = 36t -> 1.5t^2 - 4.5t - 108 = 0
\n" ); document.write( "So, t = (4.5 +- sqrt(4.5^2 - (4)(1.5)(-108)))/(2*1.5)
\n" ); document.write( "This gives t = 10.1168 hrs.
\n" ); document.write( "Therefore her speed in km/hr = 36/10.1168 = 3.558 km/hr\r
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