Final answer:
Option A and B can form a proportion.
Step-by-step explanation:
A proportion is created when two ratios are found to be equivalent or equal. In this case, ratios A and B can form a proportion if they are equal.
Let's check each option:
A. 12/16 and 30/40 can form a proportion because they are equal to 3/4.
B. 8/12 and 15/21 can also form a proportion because they are equal to 2/3.
C. 20/4 and 17/3 cannot form a proportion because they are not equal.
D. 5/9 and 80/117 can form a proportion because they are equal to 65/117.
Therefore, options A and B can form a proportion.
For example, if we look at a proportion like 1/2=3/6, these two ratios are equivalent because when simplified, 1/2 remains the same, and 3/6 simplifies to 1/2 as well. Sometimes, in real-world scenarios, proportions are used to solve problems involving scale models or maps. For instance, a map might have a unit scale that reads "1 inch = 100 feet", which is an example of a proportion showing that 1 inch on the map represents 100 actual feet.