Erica read 160 pages of her book. if she is 40% of the way done, how many pages are there in the whole book?
If 160 pages are 40% of the book
then x pages are 100% of the book
Thus in ratio form:
\(160:40\)%
\(x:100%\)%
Same as:
\(\frac{160}{0.4}=\frac{x}{1}\)
\(x=\frac{160}{0.4}=400 pages\)