Subtract 40 from 64: Calculating Remaining Milk Cartons

To solve this problem, we'll follow these steps:

• Step 1: Calculate the number of milk cartons removed
• Step 2: Subtract the removed cartons from the initial total
• Step 3: Verify the result with the answer choices

Here's how we do it:
Step 1: Calculate the total milk cartons taken away. The problem states that 4 boxes of 10 cartons each were removed:
$\text{Total Cartons Removed} = 4 \times 10 = 40$

Step 2: Subtract the removed cartons from the initial total of 64:
$\text{Remaining Cartons} = 64 - 40 = 24$

Step 3: Compare with choices, and we see that 24 is indeed one of the choices provided (Choice 2).

Therefore, the number of milk cartons left on the warehouse shelf is $24$.