the conservative and liberal democrat parties that have formed a coalition government in westminister won only
20% of the scottish vote, combined, in the past elections.

이 문장인데요... 중간에 갑자기 combined만 떡 하니 나와서... 해석이 안되네요...
combined가 여기서는 어떻게 쓰인건가요??
문법적으로 어케 되는건가요??