Daniela, the pharmacy technician returned to the stock bottle of 250 milliliter of lithium suspension to the shelf. She used 175 milliliter to fill the patients prescription. How many milliliter were in the lithium stock bottle before Daniela used any of it

She returned the bottle of 250 milliliter in lithium stock where another 175 milliliter of lithium was already present in the stock.

Quantity of lithium before return = 175 milliliter.

Quantity of lithium that she returned = 250 milliliter.

Total stock would be now = 175 + 250 = 425 milliliter.

So, there was 425 milliliter of lithium before she used any of it.

Hence, 425 milliliter is the final answer.