Answer:
She consumes 30 blue ray disk and 60 DVD respectively.
Step-by-step explanation:
Consider the provided information.

Calculate marginal utility of good
Differentiate with respect of x and y.


Her consumption of Blu-ray disks (X) with a price of $40 and Y is her consumption of DVDs with a price of $10.
The ratio of marginal utility of good x to y is equal to the price ratio:

Substitute the respective values.




She has $1800 with which to spend on the two goods.
Her consumption of Blu-ray disks (X) with a price of $40 and Y is her consumption of DVDs with a price of $10. She has $1800 with which to spend on the two goods.
Therefore, 

Substitute the value of y in above equation.



Thus, 
She consumes 30 blue ray disk and 60 DVD respectively.
Answer:
The solution is (-∞, 0.125) ∪ (0.18,∞)
Step-by-step explanation:
we have

This is a compound inequality
or 
Remember that

so
-----> the solution is the interval (0.18,∞)
----> the solution is the interval (-∞, 0.125)
The solution of the compound inequality is
(-∞, 0.125) ∪ (0.18,∞)
Explanatory variable, or the independent variable. The two are interchangeable, but explanatory is more likely to be used in statistics, and independent variable is used practically everywhere else.