X= -2
look at the 6x-12 you divide -12 by 6 and get x=-2
Given:
Total number of students at Colfax Middle School = 270
Ratio of boys to girls is 5:4.
Total number of students at Winthrop Middle School = 180
Ratio of boys to girls is 4:5.
The two schools hold a dance and all students from both schools attend.
To find:
The fraction of the students at the dance are girls
Solution:
There are 270 students at Colfax Middle School, where the ratio of boys to girls is 5:4.

Number of boys 
Number of girls 
There are 180 students at Winthrop Middle School, where the ratio of boys to girls is 4:5.

Number of boys 
Number of girls 
Now,
Total number of students in both schools 

Total number of girls in both schools 

The fraction of the students at the dance are girls is



Therefore, the required fraction is
.
Answer:
(a) The data set is a function, since for each input value {3,4,6,11} there is a single output value {5,7,11,21}
(B) A function is a mathematical relationship that associates one or more inputs with a single output value. So that the data set is not a function, there should be - for one or more values of the input - more than one output.
for example, if for the input value {3} there were two outputs {5, -5} then, the data set would not be a function.
The frelation
is not a function because:
When x = 1, y = +1 and y = -1.
(c) The set of data provided can be represented by the equation of a line of the form y = mx + b
The slope is:


m = 2

b = 5 - 2*3
b = -1
Then, the function is:
y = 2x-1
You can substitute any of the points shown in the equation and check that equality is satisfied, for example:
(11 , 21)
y = 2 (11) -1
y = 22-1
y = 21. The equation is satisfied. The same goes for the rest of the values.
Answer: The answer is 1/3