Question

Terra bought two bottles of juice a day for 15 days on the 16th day terra bought seven bottles of juice

Answer 1

In three and a half days she will need more juice. 

Answer 2

Terra bought 37 bottles of juice. 2 bottles each day for 15 days is 30 bottles. Add another 7 bottles of juice,(for the 16th day) and you get 37 bottles of juice.