A answer of the explanation for the explanation is the answer
The samples he chose may not be a representative sample because the number of students per foreign language class may not be the same. One class may have a very large number of students while another may have only a few. Taking equal number of students per class is not a representative sample.<span />
30 + x0.15=y is the first equation
15+x0.20=y is the second equation
Where in both x equals the amount of days it takes and y is your out come
You can solve this problem two ways one by finding the common denominator or just multiply x until you get the same awnser between the both of them
1+4=5 & 2+5=12 THE REASON FOR 2+5=12 IS <span>5+2+5=12
</span>So the same is for the next