Question 535084
Let {{{s}}} = speed going to lake in km/hr
Let {{{d}}} = distance to lake in km
To lake:
{{{ d = s*5 }}}
Trip back:
{{{ d = 45*6 }}}
{{{ d = 270 }}}
By substitution:
{{{ 270 = 5s }}}
{{{ s = 54 }}} km/hr