Answer:
25 degrees
Step-by-step explanation:
We need to set up a difference. The high is 77 and the low is 52, so let's subtract 52 from 77:
    77
-   52
______
From the rightmost column, we have 7 - 2, which equals 5. So, put 5 there:
    77
-   52
______
       5
Now, look at the left column. We have 7 - 5, which equals 2. So put 2 there:
    77
-   52
______
    25
Thus, the answer is 25 degrees.