Question 715159
Since they are heading directly opposite
eachother, you can think of 1 train as
standing still and the other train as
moving at the sum of their speeds
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Let {{{ t }}} = time in hrs
{{{ 442 = ( 90 + 80 )*t }}}
{{{ t = 442 / 170 }}}
{{{ t = 2.6 }}}
{{{ .6*60 = 36 }}}
In 2 hrs and 36 min, they will be 442 mi apart