Answer:
180 pages
Step-by-step explanation:
let x be the number of pages in the book , then
[tex]\frac{7}{9}[/tex] x + 40 = x ( multiply through by 9 to clear the fraction )
7x + 360 = 9x ( subtract 7x from both sides )
360 = 2x ( divide both sides by 2 )
180 = x
The total number of pages in the book is 180