1st one:
pqs + pus + x = 270 (=360-90) (sum of angles of quadrilateral)
a) alone is ob not sufficient and b) alone is also not sufficient
a&b) qr=rs thus, rqs = rsq and similarly, tsu=tus.
pqs = 180 - rqs (straight line) and pus = 180- tus
thus x -tus -rqs = -90. also rqs = rsq and tsu = tus
thus x - tsu - rsq = -90.
Also tsu + rsq +x = 180 -> 2x - 180 = -90 or x=45
Sufficient
IMO C

2nd:
circular table arrangements = (n-1)! (for n people)
as n=5, 4! = 24
IMO C