$$\int \operatorname{cosec}(x-a) \cdot \operatorname{cosec} x d x=$$

The contrapositive of the inverse of $\mathrm{p} \rightarrow(\mathrm{p} \rightarrow \mathrm{q})$ is

The area enclosed between the parabola $y^2=4 x$ and the line $y=2 x-4$ is

There are 3 sections in a question paper and each section contains 5 questions. A candidate has to answer a total of 5 questions, choosing at least one question from each section. Then the number of ways, in which the candidate can choose the questions, is