This question belongs to unitary method .
Now the number of hours in which Joan reads 75 pages in = 4 hours.
So,,
Joan will read 1 page in = [tex]\frac{4}{75}[/tex] hours
And Joan will read 250 pages in= [tex]250 * \frac{4}{75} = 13.33[/tex] hours.
Hence Joan will read 250 pages in 13.33 hours.
