Fraction problem

Question

george was reading a story book. he read an equal number of pages each day. after 5 day, he has 2/3 of the storybook left. after another 7 days, he had 21 pages left. how many pages were there in the storybook in all?

Answer 1

1 - 2/3 = 1/3 read after 5 days

(1/3)/5 = (1/3)(1/5) = 1/15 page per day

12(1/15) = 12/15 pages read after 7 days

1 - 12/15 = 3/15 = 1/5 pages left after 7 days

(1/5)p = 21

5(1/5)p = 21(5)

p = 105 pages

Answer 2

he read 1/3 of the pages in 5 days

(1/3)/(5/1) = (1/3)(1/5) = 1/15 of the pages are read each day

2/3 = (1/15)(7) + 21

2/3 = 7/15 + 21

21 = 2/3 - 7/15 = 10/15 - 7/15 = 3/15 = 1/5

21 = 1/5 of the book

5 x 21 = 105 pages

check:

1/15 of 105 = 7 pages a day

5 days + 7 days = 12 days

12 days x 7 pages a day = 84

105 - 84 = 21 pages left