I have to assume that you want the answer in Spanish *but without using accents).
Usa las siguientes variables:
d = numero de habitaciones dobles
i = numero de habitaciones individuales
Por la primera premisa:
d + i = 180
Por la segunda premisa, los costos son tales que:
78d + 72i = 7839
Para resolver ese sistema podemos despejar una de las variables de la primera ecucacion y sustituir en la segunda:
i = 180 - d
78d + 72 (180 - d) = 7839
78d + 12960 - 72d = 7839
De aqui ya veo que va a dar un numero negativo para el numero de habitaciones dobles, asi que supongo que algun dato en el enunciado esta equivocado.
6d = 7839 - 12960 = -5121
=> d = -5121 / 6 = - 853.5
Al corregir los datos podras seguir el procedimiento que te he explicado para encontrar la solucion.
So what I would do is first multiply the mean by 4 and that is the total u need, 146.5, to have a mean of 36 and 5/8. Next I add the lengths given, which is 110.625, and then I would subtract it from 146.5 which is 35.875 which is 35 and 7/8. You can also check the answer by finding the mean of the 4 numbers and determining if it comes out to 36 and 5/8. The answer is C. Hope this helps!
Question:
What is the common denominator of
in the complex fraction 
A) 
B) 
C) 
D) 
Answer:
Option D : 3 is the common denominator
Explanation:
It is given that the complex fraction 
We need to determine the common denominator of
from the complex fraction.
Let us consider the fraction 
To find the common denominator, let us take LCM.
Thus, rewriting the above fraction as,

The LCM can be determined by multiplying the denominators.
Thus, we get,

Thus, the common denominator is 3.
Hence, Option D is the correct answer.
The prefix centi- means 10-2
:)
Its B just without the ^