#self doubt

Question

Two boys start running from a point on an oval track at the same time in the same direction. The first boy takes 18 minutes to run one lap and the second boy takes 12 minutes to run a lap. How many minutes after the start will the faster boy have a two-laps lead over the slower boy?

 

The given answer is 72.

Answer 1

Apologies for the handwriting :(

Answer 2

Fast guy takes 12 min to complete 1 lap and in the same 12 min slow guy completes 2/3^rd lap.
The difference between them after first 12 min is 1-2/3 = 1/3^rd lap

Now this difference of 1/3 needs to become 2

=>1/3 *x =2

x=6

so it takes six more laps of 12 min to form a difference of 2.

so 12 min*6 =72 min