Three servants were punished after they tried to escape. two were white, and one was black. the white servants had their contracts extended; the black servant was ordered to serve for the rest of his life. why were the punishments different

The race of the servants was the differentiating factor. With the white servants, it was common for a punishment to be much less severe than that given to black servants. Since blacks were considered to be "not a person" (note the 3/5 Compromise for evidence), it was common to treat them in such ways that only exacerbated the differences between whites and blacks.