One-Step Equations · Superchallenge problem

A seesaw balances when (weight $\times$ distance from the middle) added up on one side equals the same total on the other side. On the left side, Ana ($32$ kg) sits $1.5$ m from the middle and her dog ($8$ kg) sits $2.5$ m from the middle. On the right side, Ben ($40$ kg) sits alone. How many meters from the middle must Ben sit to balance the seesaw?