Lever had been invented since the Stone Age, so it is impossible to say who and where it was invent. From the earliest remaining writing, lever was provided by Archimedes during 3rd century BC. Most to exert a large force over a small distance at one end by exerting only a small force over a greater distance at the other. In ancient China there is a Chinese style lever. The Chinese lever is used for trading; moreover, in ancient China they use lever to calculate the mass for goods, than decide the price by where they place the object.
source: https://baike.baidu.com/item/%E7%A7%A4/2318629?fr=aladdin
https://en.wikipedia.org/wiki/Lever https://en.wikibooks.org/wiki/Wikijunior:How_Things_Work/Lever
https://www.google.ca/search?q=lever&source=lnms&tbm=isch&sa=X&ved=0ahUKEwidkvO5yOPXAhUG4WMKHas8B34Q_AUICigB&biw=1366&bih=618
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