Step 1: Write the second number under the first number so that the ones, tens, and hundreds places are lined up.

Step 2: Look at the ones column. 3 is less than 4, so take 1 ten from the tens place, change the ten to 10 ones, and add the 10 ones to the ones place. This is called regrouping.
Then, subtract the ones column (13 - 4 = 9). Write the 9 in the ones place of the difference.

Step 3: Subtract the tens column (7 - 0 = 7). Write the 7 in the tens place of the difference.

Step 4: Subtract the hundreds column (7 - 4 = 3). Write the 3 in the hundreds place of the difference.