Question 1086555
Let {{{ -w }}} = the windspeed the plane sees
when it travels from Paris to NY
{{{ 550 - w }}} mi/hr is the plane's speed 
when it travels from Paris to NY
----------------------------------------
The wind is in the opposite direction on the return trip, so
{{{ 550 + w }}} mi/hr is the plane's speed
when it travels from NY to Paris
----------------------------------------
Let {{{ t }}} = time in hrs for the plane to travel
from NY to Paris
{{{ 1.2t }}} = time in hrs for the plane to travel
from Paris to NY
----------------------------------------
Equation for Paris to NY:
(1) {{{ 3600 = ( 550 - w )*1.2t }}}
Equation for NY to Paris:
(2) {{{ 3600 = ( 550 + w )*t }}}
---------------------------------
(2) {{{ t = 3600 / ( 550 + w ) }}}
and
(1) {{{ 3600 = ( 550 - w )*1.2*( 3600 / ( 550 + w ) ) }}}
(1) {{{  550 + w   = 1.2*( 550 - w ) }}}
(1) {{{ 550 + w = 660 - 1.2w }}}
(1) {{{ 2.2w = 110 }}}
(1) {{{ w = 50 }}}
The wind speed the plane sees when flying from
Paris to NY is -50 mi/hr ( headwind, not a tailwind )
-------------------------------
check:
(2) {{{ 3600 = ( 550 + w )*t }}}
(2) {{{ 3600 = ( 550 + 50 )*t }}}
(2) {{{ 3600 = 600t }}}
(2) {{{ t = 6 }}} hrs
and
(1) {{{ 3600 = ( 550 - w )*1.2t }}}
(1) {{{ 3600 = ( 550 - 50 )*1.2t }}}
(1) {{{ 3600 = 500*1.2t }}}
(1) {{{ 3600 = 600t }}}
(1) {{{ t = 6 }}} hrs
OK