Answer:
70 pages
Explanation:
Since Daniel has read 70% of the book he has 100% - 70% or 30% of the book left to read. This 30% is 21 pages. We can write this equation, where x is the number of pages in the book:
0.3x = 21
(0.3 is equivalent to 30%)
We divide by 0.3 on both sides of the equation to get:
x = 70 pages