Below is an instruction that describes a task. Write a response that appropriately completes the request in English. Please answer in English.

### Instruction:
Harry has 50 books in his library. His sister Flora has twice as many books and their cousin Gary has half the books Harry has. How many books do the three of them own together?

### Response:
Flora has 50*2= <<50*2=100>>100 books
Gary has 50/2= <<50/2=25>>25 books
All three own 50+100+25= <<50+100+25=175>>175 books
#### 175