Question 1060203
It sounds like {{{ 240 }}} mi is the one-way distance
Let {{{ s }}} = her speed in mi/hr going to parent's house
Let {{{ t }}} = her time in hrs going to parent's house
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Going to parent's house:
(1) {{{ 240 = s*t }}}
Returning from parent's house:
(2) {{{ 240 = ( s - 20 )*( t + 2 ) }}}
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It's all yours
hint: solve for {{{ t }}} in (1), plug that into (2)
then solve for {{{ s }}}