Help me please I'm very confused about this!

At school there are 526 students and 263 are girls about how likely is it that a randomly chosen student will be a boy

The general form of the quetion of a circle is ax^2+by^2+cx+dy+e=0 where a=b=0 if the circle has a radius of three units and the center lies on the y axis which set of values of a, b, c, d, and e might correspond to the circle

Simply 8x squared + 5(7x squared- x) - 2x =