Carlos read a total of 28 books in July and 30 books in August, so he read 28 + 30 = 58 books in those two months.
His goal was to read 100 books during his summer vacation, so he still needs to read 100 - 58 = 42 books to reach his goal.
Therefore, Carlos must have read 42 books in June to reach his goal.
#### 42
The answer is: 42
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
If Carlos read a total of 28 books in July and 30 books in August, and his goal was to read 100 books during his summer vacation, how many books did Carlos read in June to reach his goal?

### Answer:
