Rules:
The "(" sign in the interval corresponds to the ">" sign.
The ")" sign in the interval corresponds to the "<" sign.
The "[" sign in the interval corresponds to the ">=" sign.
The "]" sign in the interval corresponds to the "<=" sign.
When the infinity value is present in the interval, the signs used are "(" or ")" because the infinity value can never be included in the interval.
For this example we have:
x<7.8 corresponds to (-infinity, 7.8)
x>7.8 corresponds to (7.8, infinity)
x>=7.8 corresponds to [7.8, infinity)
x<=7.8 corresponds to (-infinity, 7.8]
