In the first step, Anna solved 7 × 2.
In the second step, Anna solved 20 × 2.
20 × 2 is equal to 40, which is equivalent to 4 tens.
Then, Anna added the 1 ten that was regrouped to get 5 tens.
So, Anna wrote a 5 to represent the 5 tens, which is 50 in the final calculation.