What is the missing reason for the second step in the proof below?

1/3(x-10)=-4 solve for x with steps

(01.02 lc) angle abc has point e on ray ba and point d on ray bc. points e and d are equidistant from point b. to bisect angle abc, which of the following needs to be identified for the construction? the distance between points e and d the point in the angle that is equidistant from points e and d the endpoint of rays ba and bc the point outside of the angle that is equidistant from points e and d

Use the quadratic formula to solve the equation. if necessary, round to the nearest hundredth. x^2 - 20 = x a. 5, 4 b. -5, -4 c. -5, 4 d. 5, -4