Geographical problem

Let the time taken by a ray of sunlight to cross a longitude be x

$\frac {60}{x}$ =N.o. of longitudes crossed in an hour

N.o. of longitudes crossed in a day= $\frac {60}{x}$ x 24

By given there are 360 longitudes in the earth

$\Rightarrow$ $\frac {60}{x}$ x 24 = 360

$\Rightarrow$ x= $\frac {1440}{360}$

$\Rightarrow$ x=4

Therefore sunlight takes 4 minutes to cross a longitude