Alright, lets get started.
Zach has 3/4 hour to play video games.
Lets converts it into minutes.
[tex]\frac{3}{4}[/tex] means [tex]\frac{3}{4} *60 = 45[/tex] minutes.
It takes him 1/12 hour to set up the system means he has [tex]\frac{1}{12} *60 = 5[/tex] minutes to set up the system.
So, he has left time for playing = [tex]45-5 = 40[/tex] minutes
Each round of his favorite game takes 1/6 hour means [tex]\frac{1}{6}*60 = 10[/tex] minutes for each round.
It means he has 40 minutes for playing and each round takes 10 minutes.
So, number of rounds he can play= [tex]\frac{40}{10} = 4[/tex]
He can play 4 rounds of his favorite game. : Answer
Hope it will help :)