Ken, Justin, and Tiff have read a total of 90

books from the library. Justin read 3 times

as many books as Ken and Tiff read 2

times as many as Justin. How many books

did Justin read?

Okay so we gonna use k for Ken and j for Justin and T for Tiff. we are gonna try to use one letter to solve this in order for It to be more efficient and easy. so if Justin reads 3 times the amount of Ken than that is just basically 3k. and if Tiff reads twice as much as Justin than it's basically 6k because Justin is reads 3 times as Ken and that times 2 is 6k. so we are solving for k in order to know how much Ken reads. so k (for Ken) + 3k (for justin) + 6k (for tiff) leaves you with 9k and they read 90 books in total. so 10k=90. so than you divide it which results in k=9. lastly if Justin reads 3 times as much as Ken than all you have to do is multiply 9 * 3 and you get 27 as the answer