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

Step 2: Add the ones column (5 + 7 = 12).
12 has two digits, but both digits will not fit in the ones place. So, write the 2 in the ones place of the sum, and carry the 1 to the tens column. This is called regrouping.

Step 3: Add the tens column (1 + 2 + 1 = 4). Write the 4 in the tens place of the sum.

First, add the ones column (8 + 8 + 2 = 18). Write the 8 in the ones place of the sum, and carry the 1 to the tens column.

Then, add the tens column (1 + 9 + 8 = 18). Write the 18 in the sum.