# Why not?

This is an ellipsis. You can include the implied words in your translation. Paul asks this question to get the attention of his readers. AT: "Why could they not attain righteousness?" (See: [[rc://en/ta/man/translate/figs-ellipsis]] and [[rc://en/ta/man/translate/figs-rquestion]])

# by works

This refers to things that people do to try to please God. You can make this explicit in your translation. AT: "by trying to do things that would please God" or "by keeping the Law" (See: [[rc://en/ta/man/translate/figs-explicit]])

# as it has been written

You can indicate that Isaiah wrote this. You can also translate it in an active form. AT: "as Isaiah the prophet wrote" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-activepassive]])

# in Zion

Here Zion is a metonym that represents Israel. AT: "in Israel" (See: [[rc://en/ta/man/translate/figs-metonymy]])

# stone of stumbling and a rock of offense

Both of these phrases mean basically the same thing and are metaphors that refer to Jesus and his death on the cross. It was as if the people stumbled over a stone because they were disgusted when they considered Jesus' death on the cross. (See: [[rc://en/ta/man/translate/figs-doublet]] and [[rc://en/ta/man/translate/figs-metaphor]])

# believes in it

Because the stone stands for a person, you may need to translate "believes in him."