If for any two events $$\mathrm{A}$$ and $$\mathrm{B}, P(A)=\frac{4}{5}$$ and $$P(A \cap B)=\frac{7}{10}$$, then $$P(B / A)$$ is equals to:

Five fair coins are tossed simultaneously. The probability of the events that atleast one head comes up is:

Assertion (A): Two coins are tossed simultaneously. The probability of getting two heads, if it is known that at least one head comes up, is $$\frac{1}{3}$$.

Reason (R): Let E and F be two events with a random experiment, then $$\mathrm{P}(\mathrm{F} / \mathrm{E})=\frac{\mathrm{P}(\mathrm{E} \cap \mathrm{F})}{\mathrm{P}(\mathrm{E})}$$.

Assertion (A): $$\int_\limits2^8 \frac{\sqrt{10-x}}{\sqrt{x}+\sqrt{10-x}} d x=3$$

Reason (R): $$\int_\limits a^b f(x) d x=\int_a^b f(a+b-x) d x$$