Reenu type 540 words during half an hour. How many words would she type in 8 minutes?
More the time, more will be the no. of words typed. So it is a direct proportion.
Half an hour = 30 minutes
Let the no. of words be x, 
⇒ 30 × x = 540 × 8
⇒ x = 
= 144 words
15