Can someone please help... I don't know what to answer... I will give brainly the most useful account

Step-by-step explanation:
20 25
↓ ↓ ↓ ↓
10 2 5 5
↓ ↓
5 2
20 = 5 × 2 × 2
25 = 5 × 5
GCF = 5