C <span>represents the unit rate
hope that helps</span>
55% of 120 is just 66
add that with 120, 186
so... 186 books
If a number is positive, Leila's theory that 75% of a number will always be greater than 50% of another number is <em>true</em>;<em> </em>however, if both numbers are negative, or if the number of which she finds 50% is much greater than the number of which she finds 75%, Leila's theory could be incorrect.
This inequality shows that Leila is correct:

(which simplifies to

)
This inequality shows that Leila is incorrect:

(which simplifies to

)
Hope this helps!
First one:
The circumference of the whole circle is (2π x the radius),
and 60° is (60/360) = 1/6 of the whole circumference.
Second one:
The area of the whole circle is (π x the radius²), and
the 40° sector is (40/360) = 1/9 of the whole area.
I hope this is enough help.