Step-by-step explanation:
Let "c" be the original number of classrooms.
The 1200/c was the original number of students per classroom.
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Equation:
1200/(c-4) = (1200/c)+10
Multiply thru by c(c-4)
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1200c = 1200(c-4)+10c(c-4)
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1200c = 1200c-4800 + 10c^2-40c
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10c^2-40c-4800 = 0
c^2-4c-480 = 0
Factor:
(c-24)(c+20) = 0
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Positive solution:
c = 24 (# of classrooms originaly planned)
We conclude that the starting average grade is 79.17%
<h3>
How to write the equation and solve it?</h3>
There are 50 students, let's say that the grades are measured between 1% and 100%.
And the average grade of the 50 students is A.
We know that after it increased by 20%, the average of the grades is 95.
Then we just need to solve the percentage equation:
95 = A*(1 + 20%/100%) = A*(1.2)
95/1.2 = A = 79.17
We conclude that the starting average grade is 79.17%
If you want to learn more about percentages:
brainly.com/question/843074
#SPJ1
we are given

we can see that
degree of numerator = degree of denominator =2
so, we can divide both numerator and denominator by n^2
and we get


now, we can simplify it

now, we can plug n=inf



...............Answer
Assuming x is the missing angle, and knowing that complimentary means 90, subtract 90-73 to get 17.