document.write( "Question 1003841: Super confused, need help by today-\r
\n" ); document.write( "\n" ); document.write( "Lisa travels at 30km/h on the way to visit a friend who lives 90 km away. How fast must she go on the return trip if she wants her average speed for the whole trip to be 40km/h? and 50km/h? and 60km/h? \n" ); document.write( "

Algebra.Com's Answer #620453 by josgarithmetic(39620) $\"\"$ $\"About$

You can put this solution on YOUR website!
That set of questions is for three different resulting values for what is the same variable. \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Basic travel rates rule is RT=D to relate rate, time, and distance.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Setup a data table, fill in what is given, use variables if possible for what is not known, look for equations to form; solve the equations, equation, or system of equations as fits the question or objectives.\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "

\r\n" );
document.write( "             rate           time           distance\r\n" );
document.write( "\r\n" );
document.write( "GOING         30                     90\r\n" );
document.write( "\r\n" );
document.write( "RETURN        r                         90\r\n" );
document.write( "\r\n" );
document.write( "Total                                   180\r\n" );
document.write( "

\r
\n" ); document.write( "\n" ); document.write( "The speed for the whole trip is $\"180%2F%2890%2Fr%2B3%29\"$ .\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let P be the average rate for the whole round trip.
\n" ); document.write( " $\"highlight%28P=180%2F%2890%2Fr%2B3%29%29\"$ .
\n" ); document.write( "Expect P to be any given constant, positive value greater than 30; solve the formula for r. \n" ); document.write( "

\n" );