John can create 3 apps in 6 weeks while Ben can do the same job in 2 weeks. How many weeks would it take them to create 10 apps together?

5 weeks.

Step-by-step explanation:

John can create 3 apps in 6 weeks, so his rate is (3 apps / 6 weeks) = 1/2 app per week.

Ben can do same job i. e. 3 apps in 2 weeks, so his rate is (3 apps / 2 weeks) = 3/2 app per week.

Their combined rate is (1/2 + 3/2) = 4/2 = 2 apps per week.

It means they together can create 2 apps in 1 week.

So, they together can create 10 apps in 5 weeks.