The left and right page numbers of an open book are two consecutive integers whose sum is 303. Find these page numbers.

Answer 1

easy way:
they must be just about half way, so 303/2 = 151.5
So the pages must be 151 and 152
(sure enough 151+152 = 303)

formal way:
let the two consecutive integers be n and n+1
n + n+1 = 303
2n = 302
n = 151
so the numbers are 151 and 152