Question 705603
Yhey are moving apart at the sum of their speeds
{{{ 55 + 45 = 100 }}} mi/hr
They will be 400 mi apart in {{{ t }}} hrs
{{{ d = r*t }}}
{{{ 400 = 100t }}}
{{{ t = 400/100 }}}
{{{ t = 4 }}}
They will be 400 mi apart in 4 hrs