Answer:
2
Step-by-step explanation:
- Factors of 10: 1 , 2 , 5 , 10
- Factors of 18: 1 , 2 , 3 , 6 , 9 , 18
- Factors of 20: 1 , 2 , 4 , 5 , 10 , 20
- Factors of 36: 1 , 2 , 3 , 4 , 6 , 9 , 12
The answer is 2 because it appears more then 1 which means that it is the highest common factor aka HCF
Hope this helps
