Question

If Karen uses her cell phone for more than 30 hours a month, which company should Karen choose? Why?

Answer 1

Karen should use company J.

Answer 2

Your questions asks which company is the best for Karen to choose.

Lets look at Company J first.

Company J charges a subscription fee of $30 per month plus $1 per hour of use.

Alright, Karen used 30 hours in one month, so we would have to add one dollar of an hour of use. So $1 + 30 would be $30. Now we add the other $30 because Company J charges a fee of $30 per month. $30 + $30 would be $60 in total for Company J.

Company K charges no monthly fee, but charges $2 for every hour of use.  

Now, if Karen uses more than 30 hours a month, then $2 × 30 hours of use, that would be $60.

What would be the best Company to choose?

Remember, Karen uses more than 30 hours a month, I just took 30 for an example. I would say Company J is the best Company to choose.

Why?

Because Karen uses MORE than 30 hours a month, suppose it's 40, then Company J would charge 30 dollars fee per month plus 1 dollar per hour of use, which would be 40 + 30. In total that's 70 dollars per month.

Company K would Charge 2 dollars per every hour of use, and no monthly fee. So 2 × 40 would be 80 dollars per month.

Hope this helped!~