Final answer:
To compare triangle sides, Irene can use proportions. For the unknown side in triangle B of length x, the ratio of its length to the corresponding length in triangle A is x/30 = 1/10.
Step-by-step explanation:
To compare the lengths of the sides of a triangle, Irene can use proportions. Let's say the unknown side length in triangle B has a measure of x units. The ratio of the length in triangle B to the corresponding length in triangle A is x/30 = 0.5/5. We can solve this proportion by cross-multiplying and simplifying the equation. So, x/30 = 1/10.