Question 1104965
Let {{{ s }}} = Peter's speed in km/hr
{{{ 4s }}} = Ben's speed in km/hr
Let {{{ t }}} = Peter's time in hrs to walk to the
point where he is met by Ben
Let {{{ d }}} = distance in km that Peter travels
until he meets Ben
---------------------------------------
Peter's equation:
(1) {{{ d = s*t }}}
Ben's equation:
(2) {{{ 20 + ( 20 - d ) = 4s*t }}}
----------------------------
(2) {{{ 40 - d = 4s*t }}}
(2) {{{ d = 40 - 4s*t }}}
----------------------------
(2) {{{ s*t = 40 - 4s*t }}}
(2) {{{ 5s*t = 40 }}}
(2) {{{ s*t = 8 }}}
(2) {{{ d = 8 }}}
Peter has walked 8 km when they meet
--------------------------------------
check:
(2) {{{ 40 - d = 4s*t }}}
(2) {{{ 40 - 8 = 4*s*t }}}
(2) {{{ 32 = 4s*t }}}
(2) {{{ s*t = 8 }}}
OK