Question 1129054
Let {{{ s }}} = speed of boat in still water
{{{ s + 5 }}} = speed going with the current
{{{ s - 5 }}} = speed going against the current
Let {{{ d }}} = the one-way distance
----------------------------------------------------
Going with the current:
(1) {{{ d = ( s + 5 )*3 }}}
Going against the current:
(2) {{{ d = ( s - 5 )*8 }}}
--------------------------------
{{{ ( s + 5 )*3 = ( s - 5 )*8 }}}
{{{ 3s + 15 = 8s - 40 }}}
{{{ 5s = 55 }}}
{{{ s = 11 }}}
The speed in still water is 11 km/hr
-------------------------------------------
check:
(1) {{{ d = ( 11 + 5 )*3 }}}
(1) {{{ d = 48 }}} km
and
(2) {{{ d = ( 11 - 5 )*8 }}}
(2) {{{ d = 48 }}} km
OK