Carlos read 28 books in July and 30 books in August.  He needed to read 100 books during his summer vacation. If Carlos read some of the books in June, calculate the number of books that Carlos read in June to meet his goal?
Carlos read 28 books + 30 books = 
<gadget id="calculator">28+30</gadget>
<output>58</output>
58 books.
He needed to read 100 books - 58 books = 
<gadget id="calculator">100-58</gadget>
<output>42</output>
42 books in June.

<result>42</result>