Answer:
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.
