For this case we have the following system of equations:

To solve, we clear "x" from the second equation:

We substitute "x" in the first equation:

We clear the value of the variable "y":

We look for the value of the variable "x":

Thus, the solution of the system is given by:

Answer:

Option D
Answer:
D (We can extend all the expressions)
Answer:
Changes in gas equals -5 times 6
After six hours the changes in gas were -30
Step-by-step explanation: