If (x,-3) is a solution to the equation 4x = 5y - 1, what is the value of x?

Based on what i know about mean, this doesn't add up.

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

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