Question 514903
Going up:
{{{ d = r*2.5 }}}
going down:
{{{ d = ( r + 3 )*1.5 }}}
By substitution:
{{{ 2.5r = ( r + 3 )*1.5 }}}
{{{ 2.5r = 1.5r + 4.5 }}}
{{{ r = 4.5 }}}
So,
{{{ d = 2.5*4.5 }}}
{{{ d = 11.25 }}}
check:
{{{ d = ( r + 3 )*1.5 }}}
{{{ d = 7.5*1.5 }}}
{{{ d = 11.25 }}}
He biked {{{2d}}} ascending and descending
or 22.5 km