Pen, Pencil, and Rubber in a box are in proportion to 3 ∶ 2 ∶ 1. If the value of pen, pencil and rubber are Rs. 3, Rs. 2 and Rs. 2, respectively, and the total amount spent on the entire box is Rs. 795, then find out the number of pens in the box.
1
159
2
156
3
158
4
157