ANSWER
129
EXPLANATION
The given expression is:

Deal with the parenthesis first.


Deal with exponents,

Divide now

Multiply

You can now add to get

The order of operations is PEDMAS
First, you would divide 9/72 by 72/72 and would get .125. So every book weighs .125 kg.
Then, to find how much 80 book weigh, you multiply 80 times .125 and get 10.
Lastly, to find how many books weigh 6 kg you, keep multiplying .125 by a number until you reach 6 kg. In this case the number is 48. So 48 books weigh 6 kg.
Hope this helped! ;D
Apply the cosine double angle identity to get:
Cos 2PI/3
The equation can be used to find the time in hours,
and the time will be 2.5 hours. So the correct answer is option A.
<h3>What is an equation?</h3>
It is defined as the relation between two variables, if we plot the graph of the linear equation we will get a straight line.
Layna can paint a 350-square-foot room in 4 hours.It takes Bebe 7 hours to paint the same room.
Let t be the total time taken by both to paint.They are completing 1 job so the equation will be :

Further solving it we get;
7 t + 4 t = 28
11t = 28
t = 2.5 hours.
Therefore the equation can be used to find the time in hours,
and the time will be 2.5 hours. So the correct answer is option A.
To know more about equations follow
brainly.com/question/2972832
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