To solve this problem, we can set up a proportion using the ratio of medium to large shirts in the store.
The ratio is given as 2 to 3, or 2/3.
We know that there are already 6 large shirts in stock, which is the "3" part of the ratio.
We need to find the "2" part of the ratio, which represents the number of medium shirts to order.
Setting up the proportion:
2/3 = x/6
To cross multiply:
3x = 2 * 6
3x = 12
Dividing both sides by 3:
x = 4
Therefore, they should order 4 medium T-shirts.