Answer:
2:1 or 2
Step-by-step explanation:
*** (Ratios can be written as " a : b", or can be written as a fraction " a / b".
>> therefore 10/5 can be simplified to 2/1 )***
For every 10 notebooks, there are 5 ballpens.
Therefore, for every 2 notebooks there is 1 ballpen (The simplification).
EXTRA:
**Also remember that the ratio of notebooks to ballpens cannot be reversed into ballpen to notebook ratio, because this would change the meaning.
2/1 is not the same as 1/2 **