Question 710824
Let {{{ t }}} = the time in hours for a plane fly 700 miles and a car to go 300 miles
{{{ 700/t }}} = the plane's speed in mi/hr
{{{ 300/t }}} = the car's speed in mi/hr
given:
{{{ 700/t - 300/t = 80 }}}
{{{ 700 - 300 = 80t }}}
{{{ 80t = 400 }}}
{{{ t = 5 }}}
and
{{{ 700/t = 700/5 }}}
{{{ 700/t = 140 }}}
The speed of the plane is 140 mi/hr
check answer:
{{{ 700/t - 300/t = 80 }}}
{{{ 700/5 - 300/5 = 80 }}}
{{{ 140 - 60 = 80 }}}
{{{ 80 = 80 }}}
OK