Answer:
Proportional.
Step-by-step explanation:
Find the cross products. If they are same, then they are proportional.

Cross multiply,
1.2 * 4 .5 = 3*1.8
5.40 = 5.4
So, they are proportional.
Or
Multiply the numerator and denominator of 1.2/3 by 1.5

From this we come to know they are proportional
Or
1.2 : 3 :: 1.8 : 4.5
Product of means = 3*1.8 = 5.4
Product of extremes = 1.2*4.5 = 5.4
Product of means = product of extremes. So, they are proportional.