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.
