Tightening bike brakes typically requires three hands. If you're a person with only two hands, you need old bike inner tubes. Simply wrap the old bike inner tube around the brake pads and pull tight until the pads are the desired distance from the rim. They you can easily adjust the bolt securing the brake cable so that the cable is taut with the brake pads in that position.
You can't do this kind of repair with duct tape, which is factually not as useful as old bike inner tubes. In these times of vicious partisanship, the duct tape community is likely to vociferously attack this objective report of a key bike repair. While old bike inner tubes have much greater elasticity than duct tape, the Ode Street Tribune will not engage in mud-slinging.