Answer: a) 
(b) 
(c) 
(d) 
Explanation:
The formal description of the given sets are as follows :-
a) The set containing the numbers 5, 9, and 27.

(b) The set that contains all the natural numbers less than 2.

(c) The set containing the empty string.
We know that in formal description, the empty string is denoted with
.
Thus, the required set : 
(d) The set containing nothing at all.

Answer:
through electronics we have a electrified lighted world. our homes,are lit with light using electricity. the stereo we listen to, electricity makes it happen. tv,computers, and record turntables all need electricity. electricity makes things possible that would otherwise be either impossible or very arduous. we see sounds and enjoy them. we watch entertaining movies. we read books and do our homework with the appreciated help of electricity.
Answer:
i think its the second one
Explanation:
OSHA standards appear in the Code of Federal Regulations (CFR) <span>and was then broken down into two parts. It contains standards to ensure a </span>
Answer: Strengthened, less
Explanation:
With people spending more time on internet their relationships with existing friends have decreased due to lot of contents available on the internet. They might be friends with people miles away but they might not know their next door neighbor. As the content over the internet increases day by the day this trend shall keep on rising.