For two ratios to form a proportion they have to be equal.
To see if two ratios are equal we express them in their simplest form.
In this case we notice that in the first ratio both numbers are multiples of five, then:

In the second case we notice that both numbers are multiples of 2, then:

Since both ratios can be simplified to the same final ratio, they form a proportion.
Answer:
Building's actual height 32 meters
Building's shadow height 20 meters
Person's shadow height 1.2 meters
Person's actual height = ?
Find the person's actual height:
This is a proportion problem.
Actual height to shadow height
Building = Person
32 : 20 = x : 1.2
32 * 1.2 = 20 * x
38.4 = 20x
38.4/20 = 20x/20
1.92 = x
The person's actual height is 1.92 meters long.
32 : 20 = 1.92 : 1.2
32/20 = 1.60
1.92/1.2 = 1.60
Step-by-step explanation:
Well remember this:
When the signs are the same it is positive
When the signs are different make it negative
When you are subtracting a negative and positive, it is going to be like adding
for example:
-9 - 5 = -14
You just add 9 and 5 to get 14, the signs are different so it is going to be negative. ONLY WHEN YOU ARE SUBTRACTING NEGATIVES
You take away the 4 from the 8 which is equal to 4 then you have to barrow from the 2 to make the 4 to 14 and when you wait you are basically right your calculation is right