2000 Chevy Malibu belt

Rpentine, or timing? The serp is automatically kept tight with the belt tensioner, if it's loose or squeals, replace both the belt and tensioner, 1 bolt usually holds them on, look on the tensioner pulley, use the right size box wrench and release the tension, remove the belt, then replace the tensioner. I lock 2 wrenches together for more leverage...