Question 926661
If your rate is 2 1/2 mi/hr, then that is 
the same as 5 mi in 2 hrs, so your rate
is: {{{ 5/2 }}} mi/hr
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{{{ d = r*t }}}
{{{ 7/8 = (5/2)*t }}} 
where {{{ t }}} is in hours
Multiply both sides by {{{ 8 }}}
{{{ 7 = 20t }}}
{{{ t = 7/20 }}} hrs
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Multiply this result by {{{ 60 }}}
to get answer in terms of minutes
{{{ ( 7/20 )*60 = 21 }}} minutes
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Hope this helps- I don't know if it's
algebra or pre-algebra