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.
I believe that y is equal to -5.
y=-5
Replace w with 10 and solve for a:
10 = (a-7000/2000 + 2)
Subtract 2 from both sides:
8 = a-7000 /2000
Multiply both sides by 2000:
16,000 = a-7000
Add 7000 to both sides:
a = 23,000
You can climb 23,000 feet
The explanation is replacing w with the number of weeks ( 10) and solving for a. You can then check by replacing a with the solution and solving for w.
Answer:
a) they are corresponding angles
b) B=55° (proven)
C=55 (Angles opposite equal sides)
B+C+X=180° ( sum of angles of a triangle)
55°+55°X=180
110°+X=180°
X=180°-110°
X=70°