A plane traveled 828 miles to shanghai and back. the trip there was with the wind it took 9 hours. the trip back was into the wind the trip back took 23 hr. what is the speed of the plane still in the air what is the speed of the wind

24 mph

Step-by-step explanation:

Plane speed =x mph

Wind speed =y mph

against wind x-y 18.00 hours

with windx+y 9.00 hours

Distance = same= 864 miles

t=d/r

864 / ( x - y )= 18.00

18 ( x - y ) = 864.00

18 x -18 y = 864 1

864 / ( x + y )= 9.00

9.00 ( x + y ) = 864

9.00 x + 9.00 y = 864 2

Multiply (1) by 1.00

Multiply (2) by 2.00

we get

18 x + -18 y = 864

18 x + 18 y = 1728

36 x = 2592

/ 36

x = 72 mph

plug value of x in (1)

18 x -18 y = 864

1296 -18 y = 864

-18 y = 864 -1296

-18 y = -432

y = 24 mph

Even #  if it ends with 0, # of ways = 6*5*4 = 120 if not, 3 ways for ending digit, 5 ways for 1st digit, 5*4 for middle digits = 300 
so total ways = 420 
odd #  4 ways of ending digit, 5 ways for 1st digit, 5*4 for middle digits = 400 ways 
< 4000:  3 ways for starting digit, 6*5*4 ways for remaining digits = 360 ways 
> 3000 & < 4000  1 way for starting digit , 6*5*4 for remaining digits = 120 ways