Question 552626
Let {{{s}}} = speed in still air
Let {{{w}}} = wind speed
{{{ s + w }}} = the speed for 14 hr trip ( with the wind )
{{{ s - w }}} = the the speed for 28 hr trip ( against the wind )
-------------
With the wind:
(1) {{{ 1176 = ( s + w )*14 }}}
Against the wind:
(2) {{{ 1176 = ( s - w )*28 }}}
--------------------
(1) {{{ s + w = 1176/14 }}}
(1) {{{ s + w = 84 }}}
and
(2) {{{ s - w = 1176/28 }}}
(2) {{{ s - w = 42 }}}
Add (1) and (2)
(1) {{{ s + w = 84 }}}
(2) {{{ s - w = 42 }}}
{{{ 2s = 126 }}}
{{{ s = 63 }}}
and
(1) {{{ s + w = 84 }}}
(1) {{{ 63 + w = 84 }}}
(1) {{{ w = 21 }}}
Plane's air speed is 63 mi/hr
Wind speed is 21 mi/hr
check:
(1) {{{ 1176 = ( 63 + 21 )*14 }}}
(1) {{{ 1176 = 84*14 }}}
(1) {{{ 1176 = 1176 }}}
and
(2) {{{ 1176 = ( 63 - 21 )*28 }}}
(2) {{{ 1176 = 42*28 }}}
(2) {{{ 1176 = 1176 }}}
OK