Last Puzzles (Maths IES Brain Teaser)

A thief is running after stealing two gold bars from an ancient and sacred temple. The villagers see him running and runs after him. While running, he comes across a rope bridge. There is a warning board on the start of the bridge stating that the rope can only accommodate a weight of 130 pounds. Now the thief weighs 100 pounds and the gold bars weigh 20 pounds each. But ignoring the warning he just crosses the bridge with both gold bars. He manages to cross safely. How?

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