Biased sample of what? I need more context :)
y = -
x + 
The equation of a line in slope-intercept form is
y = mx + c ( m is the slope and c the y-intercept )
rearrange 6x + 12y = 9 into this form
subtract 6x from both sides
12y = - 6x + 9 ( divide all terms by 12 )
y = -
x +
( which simplifies to )
y = -
x + 
23x =14 this will be the answer
20% also equals 1/5, right?
So in order to find the total number of turtle nests, just find 5/5, or multiply 15 by 5.
15 x 5 = 75
There were 75 total nests