Answer:
CED = 117
Step-by-step explanation:
21x +21 = 7x +49
21x - 7x = 49 - 21
14x = 28
x = 28/14
x = 2
7x + 49
=7(2) + 49
=14 + 49
=63
180 -63 = 117
CED= 117
Answer:4.14
Step-by-step explanation:
Answer:
For the given expression: 
Step-by-step explanation:
Here, the given expression in statement form is given as:
5 X minus Y equals 6 + negative 2 X plus Y = 8
Now, converting the given statement mathematically, we get:
5X - Y = 6 + (-2X) + Y = 8
Now, considering first and the last terms,we get:
5 X - Y = 8 .... (1)
and , considering second and the last terms,we get:
6 + (-2X) + Y = 8 or, -2X + Y = 2 ......... (2)
Adding (1) and (2) , we get:
5 X - Y - 2 X + Y = 8 + 2
or, 3 X = 10
or, X = 10/3 = 3.34
Now, 5X - Y = 8
or, 
Hence, for the given expression:

To compare the two classes, the Coefficient of Variation (COV) can be used. The formula for COV is this:
C = s / x
where s is the standard deviation and x is the mean
For the first class:
C1 = 10.2 / 75.5
C1 = 0.1351 (13.51%)
For the second class:
C2 = 22.5 / 75.5
C2 = 0.2980 (29.80%)
The COV is a test of homogeneity. Looking at the values, the first class has more students having a grade closer to the average than the second class.