If Anna can read 1 page in 1 minute, then her speed is 1/1 = <<1/1=1>>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 = <<1*2=2>>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 = <<100/2=50>>50 minutes to read the book
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