Asap! will mark brainliest! ( respond asap, it's urgent! : )) what is the slope for equation y =-3x + 8

I’m stuck on this equation, anyone got the answer?

The radius of the earth is two times the radius of the moon. what fraction of the volume of the earth is the volume of the moon?

With these 5 geometry questions! pls 1.)quadrilateral abcd is inscribed in this circle. what is the measure of ∠a ? enter your answer in the box.°2.)quadrilateral abcd is inscribed in a circle. what is the measure of angle a? enter your answer in the box. m∠a= 3.)quadrilateral abcd is inscribed in this circle. what is the measure of angle b? enter your answer in the box. m∠b= °4.)quadrilateral abcd is inscribed in this circle. what is the measure of angle a? enter your answer in the box.°5.) quadrilateral abcd is inscribed in this circle. what is the measure of angle c? enter your answer in the box.°