What number belongs in the blank space below

Suppose a least-squares regression line is given by modifyingabove y with caret equals 4.302 x minus 3.293. what is the mean value of the response variable if xequals20?

What is the value of the discriminant of the quadratic equation -2x = -8x + 8 and what does its value mean about thenumber of real number solutions the equation has?

What are the excluded values? m+5/mn+3m