Answer:
129 pages.
Explanation:
Let's call
the total number of pages.
He reads
on Monday. There are 13/15 left.
on Tuesday. There are 2/3 left.
on Wednesday. There are 7/9 left.
Now, the remainder would be the difference between
and all pages read at this point
![p-(2)/(15)p-(1)/(3)p-(2)/(9)p=(45p-6p-15p-10p)/(45) =(14p)/(45)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/afbscr2k5zi1l8no4zpi0glyptr6ap9fip.png)
So, 3/4 of this is
![(3)/(4) * (14p)/(45)=(42p)/(180) =(21p)/(90)=(7p)/(30)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/zepcxv34xqbizay47r0v44etwzd07wr3ev.png)
The sum of all pages read is
![((2)/(15)+(1)/(3)+(2)/(9)+(7)/(30) )p+10=p\\((12+30+20+21)/(90))p +10=p\\(83)/(90)p+10=9\\ 10=p-(83)/(90)p\\10=(90p-83p)/(90)\\ 900=7p\\p=(900)/(7)\\ p \approx 129](https://img.qammunity.org/2020/formulas/mathematics/middle-school/bjcmxu3slj9ecypc0vt12v28ozardepop9.png)
Therefore, there are around 129 pages.