Anna can read 1 page in 1 minute. Carole can read as fast as Anna but at half the speed of Brianna. How long does it take Brianna to read a 100-page book?
If Anna can read 1 page in 1 minute, then her speed is 1/1 = 
<gadget id="calculator">1/1</gadget>
<output>1</output>
1 page per min.
If Carole can read at Anna's same speed then her speed is also 1 page per min.
If Carole is only half the speed of Brianna, then that means Brianna is twice as fast as Carole, so 2 * 1 page per min = 
<gadget id="calculator">1*2</gadget>
<output>2</output>
2 pages per min.
If a book is 100 pages long and Brianna can read 2 pages per minute, then it will take her 100/2 = 
<gadget id="calculator">100/2</gadget>
<output>50</output>
50 minutes to read the book.

<result>50</result>