If $P(A)=\frac{2}{5}$ And $P(B)=\frac{4}{5}$ , Then $P(A \cup B)$ Must Be Greater Than 1

If $P(A)=\frac{2}{5}$ and $P(B)=\frac{4}{5}$ , then $P(A \cup B)$ must be greater than 1 .