The following table have 5 items along with number of items brought and sold for each quarter for each item.
(B - Item brought initially in the quarter, S - Item sold in that quarter)
| Quarter | Q1 | Q2 | Q3 | Q4 |
| Items | B | S | B | S | B | S | B | S |
| A | 300 | 170 | 400 | 335 | 370 | 320 | 410 | 370 |
| B | 270 | 180 | 280 | 200 | 350 | 330 | 380 | 340 |
| C | 280 | 210 | 350 | 310 | 250 | 200 | 250 | 200 |
| D | 320 | 250 | 340 | 290 | 280 | 180 | 280 | 240 |
| E | 325 | 275 | 370 | 315 | 320 | 170 | 265 | 190 |
Find out the average of difference of item brought and item sold for Quarter 1.