Johnny is reading a novel for the read-a- thon. the ratio of the number of pages she read to the pages that remain to be read is 7: 3. if the book contains 500 pages in all, how many pages did johnny reed and how many pages remain left?

There are several ways to answer this question and I will use this approach. Since Johnny reads at a ratio of 7:3 it can be stated that for every 10 pages in a book containing 500 pages Johnny will read 7 of those pages. There are 50 groups of 10 in a 500-page book (50 x 10). Take the ration 7:3 times 50 and use the distributive property:  7:3(50) = (7 x 50):(3 x 50) = 350:150. Based on this Johnny has read 350 pages and has 150 pages remaining.