Răspuns:
a) 2/4=3/5 →nu formeaza o proportie
2×5≠4×3
b) 6/10=3/5 → formeaza o proportie
10×3=6×5
c) 7/3=3/5 →nu formeaza o proportie
7×5≠3×3
d) 21/35=3/5 → formeaza o proportie
21×5=35×3
e) 0,2/0,(3)=3/5 → formeaza o proportie
2/10×5=3/9×3
10/10=9/9
f) 2⁴/5²=3/5 → nu formeaza o proportie
16/25=3/5
16×5≠25×3