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It introduces the relationship between two variables and is called correlation. Proportionality or variation is state of relationship or correlation between two variables It has two types: </span>direct variation or proportion which states both variables are positively correlation. It is when both the variables increase or decrease together. On the contrary, indirect variation or proportion indicates negative relationship or correlation. Elaborately, the opposite of what happens to direct variation. One increases with the other variables, you got it, decreases. This correlations are important to consider because you can determine and identify how two variables relates with one another. Notice x = y (direct), y=1/x (indirect)</span>
Answer:
C. 15
Step-by-step explanation:
The following proportional can be set-up for the figure given:

Solve for x


Cross multiply


15 = 6x - 5x
15 = x
x = 15
The range is the output or the y values in the case of this function. The only y value on this function is 1 therefore the range is 1
You multiply 8 by 15 then again by 6 so the answer is 720
$86.62 would be the total after 15% tax.