The product of the page numbers on two facing pages of a book is 156. Find the page numbers

Let x be the page number then x+1 would be the other page number (because the pages are two facing pages which means they follow on consecutively)

Then

(x) (x+1) = 156

x^2 + x - 156 = 0

x = 12 or x = - 13 (but x can't be a negative number)

so x = 12

and the next page is 13