On Monday he reads 2 pages, on Tuesday he reads 6 pages (triple of 2: 2 + 2 + 2 = 6), on Wednesday he reads 18 pages (triple of 6: 6 + 6+ 6 = 18), on Thursday he reads 54 pages (triple of 18: 18 + 18 + 18 = 54).
Let p be the prize of a pen and m the prize of a mechanical pencils. If you buy six pens and one mechanical pencil, you spend 6p+m. We know that this equals 9, because you get 1$ change from a 10$ bill.
Similarly, if you buy four pens and two mechanical pencils, you spend 4p+2m, which is 8$, because now you get a $2 change. Put these equation together in a system:

Now, if you multiply the first equation by 2, the system becomes

Subtract the second equation from the first:

Plug this value into the first equation to get

Answer:

Option D is the right option.
Explanation:
Observe from the graph that the value of X starts at X=0 and the graph is going to the right infinitely.
So the domain of the function should be:

Hope this helps...
Good luck on your assignment..