To get sympy to simplify the expression (bx)^a(cx)^-a into (b/c)^a, you need to import the sympy library and use the simplify function. First, define the variables b, c, x, and a using the symbols method. Then, create the expression (bx)a * (c*x)-a using these variables. Finally, call the simplify function on the expression to simplify it into the desired form, (b/c)**a. This will allow sympy to simplify the expression and provide you with the simplified result.