I assume that I have to express this as a percentage of x.
120% of x is 1.2x.
40% is 2/5, so it is 1.2x * 2/5, so it is 2.4x/5, which is 4.8x/10, so it is 0.48x.
Let us test it out.
Suppose x = 100.
120% of 100 is 120.
40% of 120 is 48, which fits with our equation 0.48x.
So the answer is 0.48x