Question

25% of journey covers 5000km. how long is the whole journey?

Answer 1

25% would be 1/4 of the whole journey. If 5000km is 1/4 then, we need to multiply it by 4. 

$5.000km*4=20.000km$

Answer 2

20000km is the whole journey since 25% covers 5000 km
therefore 5000*4=20000km