If 1/8 is invested in US stocks and 1/10 invested in japanses stocks and 1/5 invested in european stocks the how much is invested in municipal bonds? How do I figure out this problem?

Assuming that the rest of the portfolio is in municipal bonds --

1 - (1/8 + 1/10 + 1/5) =
1 - (5/40 + 4/40 + 8/40) = ?