For 30 persons or fewer $10 per person. For every additional person $9 per person. Irene paid the company $390 for her department event. How many people did she cater for?

She catered for 40 people.

Step-by-step explanation:

According to the information given, you can write an equation that indicates that 30 people multiply for its cost that is $10 plus the number of people after 30 for its cost that is $9 is equal to $390. According to this, the equation is:

10 (30) + 9x = 390, where

x = number of people after 30

Then, you can solve for x:

300+9x = 390

9x=390-300

9x = 90

x=90/9

x=10

The answer is that she catered for 40 people, 30 people at a cost of $10 and 10 people for a cost of $9.