Answer :

heyDB
Multiply 2/3 * 5 to find out how many cups she used

Write 5 as a fraction with denominator 1
(5/1)(2/3) 

Combine 5/1 and 2/3 to get (5⋅2)/3. 

5⋅2/3 

Multiply 5 by 2 to get 10. 

10/3 

Exact Form: 
10/3 

Decimal Form: 
3.33333333... 

Mixed Number Form: 
1/3

She used 3 1/3 cups of oatmeal. 
5 batches
2/3 cup per batch
so
5 times 2/3=5/1 times 2/3=10/3=3 and 1/3 cups of oatmeal

answer is 3 and 1/3 cups