Please help me, please

You paint a 1/2 of a wall in 1/4 hour. how long will it take you to paint one wall

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

Determine the number of girls in a math class with 87 boys if there are 25 girls for every 75 boys