Answer:
The solution for this system is: 
Step-by-step explanation:
The problem states that we have to solve this system by the elimination method
In the elimination method, we transform the system in such a way that one variable can cancel each other. With this, we find the result of the other variable. Then, we can replace the variable we found in any of the equations, and we have the value of the variable that we had initially canceled.
In this problem, we have the following system:


If we add equations 1) and 2), the variable x is going to be eliminated





Now, we can replace the value of y in any of the equations, to find x:
I will replace in equation 2)





The solution for this system is: 
Answer:
(-4,-7)
(4,7)
(-4,-5)
(1,-1)
Step-by-step explanation:
If I understand this problem correctly the answer would be 29 more people can board the plane! Hope this helps! Comment if you have questions!!!
1. Answer x=-5
You would subtract 25 from each side of the equal sign, taking 25 away from 40 and 25 away from 25, isolating the x. So you would then have -3x=15. You would then divide each side by -3, and getting x=-5