Read this: The nationalist parties, in turn, demanded devolution to their respective constituent countries in return for their supporting the government. When referendums for Scottish and Welsh devolution were held in March 1979 Welsh devolution was rejected outright while the Scottish referendum returned a narrow majority in favour without reaching the required threshold of 40% support. When the Labour government duly refused to push ahead with setting up the proposed Scottish Assembly, the SNP withdrew its support for the government: this finally brought the government down as it triggered a vote of confidence in Callaghan's government that was lost by a single vote on 28 March 1979, necessitating a general election.

How much did Callaghan's government win a vote of confidence by?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable