If each serving size is 2 capsules, a 60-capsule bottle of vitamin D3 would contain 60/2=30 servings.
Using 30-serving bottles, to last 180 days, it would take 180/30=6 bottles of vitamin D3.
The doctor told Barry to take vitamin D3 for 180 days to help protect him from infections. The pharmacy only sold vitamin D3 in bottles containing 60 capsules, with a daily serving size of 2 capsules.  How many bottles would Barry need to buy to have enough servings to last for 180 days?