The clock in Sri's car, which is not accurate, gains time at a constant rate. One day as he begins shopping, he notes that his car clock and his watch (which is accurate) both say $12:00$ noon. When he is done shopping, his watch says $12:30$ and his car clock says $12:35$. Later that day, Sri loses his watch. He looks at his car clock and it says $7:00$. What is the actual time in hours and minutes? If the actual time is $a$ hours and $b$ minutes, what is the value of $a + b$?

Let's think step by step and output the final answer within \boxed{}.
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