Consider the question. There are 1250 pairs of shoes in the warehouse. There are 540 pairs that are blue. The rest are either green or purple. The number of green shoes is equal to the number of purple shoes. How many pairs of purple shoes are in the warehouse?
 If the answer is '355'; explain the reasoning:
1250 - 540 = 710. 710 / 2 = 355. There are 355 pairs of purple shoes in the warehouse.