The bonus works as a multiplier of 1.1x to 2x of the normal rewards (so rewards are calculated as LPTs amount * boosting multiple). The multiple you receive on the boost for the seven days is random, users will receive from 1.1x (essentially, 10% more rewards for the period than anyone who is staking LPTs without the NFT boost) up to 2x boost. This means that for instance, if base APR for staking MIN/ADA LPTs is 200% APR, by staking the NFT as well you will get 220-400% APR the first 7 days.