Question 728056
{{{ d = r*t }}}
The boat's rate is {{{ 336/7 }}} mi/hr
{{{ 144 = ( 336/7)*t }}}
{{{ t = 144*( 7/336 ) }}}
{{{ t = 3 }}} hrs
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Note that the units are miles/hr and miles, 
so you don't have to convert any units.