The answer is 14. your welcome :)
The given situation above is an example of a geometric sequence with first term equal to three and the common ratio equal to 3. For the second day, Raul used 9 bags of cement. He used 27 bags on the third and 81 on the fourth. To answer the question, add the number of bags from second to fourth day. The answer is equal to 117 bags of cement.
On the graph you just go down by two every time once you find one point like (1,-2). Basically (x,-2(x)) is what it would look like on an order pair.