For the following questions answer them individually
If $$a = \frac{\sqrt{5} + 1}{\sqrt{5} - 1}$$ and $$b = \frac{\sqrt{5} - 1}{\sqrt{5} + 1}$$, then the value of $$a^2 + ab + b^2$$ is
Out of a total of 750 students each student studies at least one of the two subjects, Physics and Mathematics. If 40% of them study Mathematics and 70% study Physics, then the number of students who study both is