CMAT Linear Equations questions

If $$x - \frac{1}{x} = y, y - \frac{1}{y} = z, z - \frac{1}{z} = x$$, there which of the following equations are true?
A. $$\frac{1}{x} + \frac{1}{y} + \frac{1}{z} = 0$$
B. $$\frac{1}{x^{2}} + \frac{1}{y^{2}} + \frac{1}{z^{2}} = 8$$
C. $$\frac{1}{xy} + \frac{1}{yz} + \frac{1}{zx} = -3$$
Choose the correct answer from the options given below:

The price of an apple is twice that of an orange. The price of an orange is thrice that of a banana.If the price of an apple increases by 10%, price of an orange increases by 30% and the price of a banana increases by 20%. Find the percentage increase in the price of 20 apples, 20 oranges and 20 bananas.

The sum of three consecutive odd numbers is 20 more than the first number. What is the middle number ?

Two oranges, three bananas and four apples cost Rs. 15. Three oranges, two bananas and one apple cost Rs. 10. I bought 3 oranges, 3 bananas and 3 apples. How much did I pay ?

If AB + C = D, find A and C given that when B = 6, D = 30 and when B = 8, D = 36.