Question 889025
An easy way to do this is to think of one
of the planes as standing still and the other approaching at 
the sum of their speeds
The equation shows the time, {{{ t }}}, when the 
planes are {{{ 125 }}} miles apart
{{{ 1300 - 125 = ( 450 + 490 )*t }}}
{{{ 1175 = 940t }}}
{{{ t = 1.25 }}}
One and a quarter hours after noon is 1:15 PM
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check:
{{{ d[1] = 450t[1] }}}
{{{ d[1] = 450*1.25 }}}
{{{ d[1] = 562.5 }}}
and
{{{ d[2] = 490t[2] }}}
{{{ d[2] = 490*1.25 }}}
{{{ d[2] = 612.5 }}}
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{{{ d[1] + d[2] = 562.5 + 612.5 }}}
{{{ d[1] + d[2] = 1175 }}}
{{{ 1300 - 1175 = 125 }}} miles
OK