Well, since 3/15 can be simplified to 1/5 by dividing the top and the bottom by 3, you would just need to find the decimal of 1/5 which is much more commonly recognized. it's .2 (becasue 1/10 would be .1 and 1/5=2/10 so .1x2=.2)
Yes the distributive property is used to expand expressions, but it is also used to make it simpler.
For an example
3(x+4) + 3(y-8)
This is the same thing as
3x + 12 + 3y -8
The correct answer is statement number 3. A line is an undefined term because it describes something that does not have width or depth. However, lines can extend its length in both side infinitely. It contains arrowheads indicating it can extend.
It does if the x values don't repeat it they repeat it doesn't