The number of order of each aircraft is an illustration of simultaneous equations.
You should order <em>7 Airbus A330-300s, 5 Boeing 767-300ERs and 9 Boeing Dreamliner 787-9s</em>
To do this, we make use of the following representations:
- <em>A represents Airbus A330-300s</em>
- <em>B represents Boeing 767-300ERs</em>
- <em>C represents Boeing Dreamliner 787-9s</em>
<em />
From the question, we have the following equations
----the number of passengers
--- the relationship between the number of planes
--- the budget
Make A the subject in 

Substitute
in 



Divide through by 15

Make C the subject

Substitute
in 



Divide through by 5

Substitute 

Multiply through by 27


Collect like terms


Solve for B

--- approximated
Substitute
in 


--- approximated
Recall that: 
So, we have:



Hence, you should order <em>7 Airbus A330-300s, 5 Boeing 767-300ERs and 9 Boeing Dreamliner 787-9s</em>
Read more about simultaneous equations at:
brainly.com/question/16763389