Pebble with scrap book. 5% of 10 is 0.5, so 0.5 subtracted by 10 units of stealth would result in 9.5 units of stealth.
Then Goob with diary. 25% of 5 is 1.25, so 1.25 added to 5 units of stealth would be 6.25.
So Pebble with scrap book would have more stealth than a Goob with diary.