Solution to Q1:
The main question is asking that by what percent the price of an overcoat has reduced?
To solve this, we need the reduction in price and the original price because
(reduction in price)/(original price) * 100 will give us the required answer.

Let us first consider statement (1) alone.
It says original price was $380. But nothing is mentioned about reduction in price. So statement (1) alone is not sufficient to answer the question.

Next consider statement (2) alone.
It implies that reduction in price is $50. But we do not know the original price.
So (2) alone is not sufficient.

Next combine both he statements together and check. On combining we get that the percentage reduction in price is (50/380)*100.

Since both statements together are sufficient to answer the question, the correct answer is (C).

Solution to Q2:
The question is asking that Is x^2 = xy?
x^2 - xy = 0 implies x(x-y) = 0 or either x= 0 or x=y.
So the question can be reframed as Is x = 0 or x= y?

Let us first consider statement (1) alone.
It says x^2 - y^2 = (x+5)(y-5) = xy -5x+5y-25.
But this is not enough to tell us whether x= 0 or x = y or not.
So (1) alone is not sufficient to answer the question.

Next consider statement (2) alone.
It says x = y.
Then obviously x^2 = xy.
So (2) alone is sufficient to answer the question.

The correct answer is hence (B).