Can someone help me it’s for a grade and I don’t really understand it

We just started the introduction into circles and i have no idea how to do this.

What is the measure of angle x? answer

Find the equation of a line that is perpendicular to line g that contains (p, q). coordinate plane with line g that passes through the points negative 3 comma 6 and 0 comma 5 3x − y = 3p − q 3x + y = q − 3p x − y = p − q x + y = q − p