A right angle degree is always 90 degrees, or 1/4 of the full amount of degrees, which is 360. 90 degrees, is also pi/2 radians, which you will learn in trigonometry and pre-calc.
70% of the votes means that every 100 people, 70 went to cast their ballot, or 7 every 10. Now in the club there are 9 groups of 10 people, so 9x7 = 63 people