RRB RPF Constable 04 Feb 2019 Solved Paper

The ratio of pen, pencil and eraser to a box is 3 ∶ 2 ∶ 1. If pen, pencil and eraser prices are Rs. 3, 2 rupees and 2 rupees respectively, and the amount spent on the box is Rs. 555, then find out the number of pen in the box.