Emmanuel read 150 pages in 5 hours. how long would it take him to read 230 pages?

I'd begin by figuring Emmanuel's reading rate.  It is 150 pages in 5 hours, which can be re-written as 

150 pages         30 pages
 =  
 5 hours                1 hour

or 30 pages per hour.  

We could then write the equation of two ratios:

30 pages        230 pages
 =  
 1 hour                   x

where x represents the length of time required to read 230 pages.

Cross multiplying:  (30x pages) = (230 pages)(hour)

Cancel "pages."  Then 30x = 230 hours.

Divide both sides by 30:     30x  =  230 hours
                                             
                                            30            30

x = 7.6666 hours, or  x= 7 2/3 hours

4should be the last one n=4