(a) What operation on both sides of the equation $4 x = 20$ isolates the variable on one side? There may be more than one correct answer.
A. Multiplying by $1 / 4$
B. Adding $4$
C. Subtracting $4 x$
D. Multiplying by $4$
E. Dividing by $20$
F. Dividing by $4$
G. Dividing by $4 x$

(b) Give the solution of the equation $4 x = 20$.
$x =$ help (numbers)