What is the second term of the proportion where 21:x = 35:5?

To determine the second term of the proportion 21:x = 35:5, we can use the concept of cross-multiplication. In a proportion, the product of the means equals the product of the extremes. This means we can set up the equation:

21 * 5 = 35 * x.

Calculating the left side gives us:

105 = 35x.

To solve for x, we divide both sides of the equation by 35:

x = 105 / 35.

When you perform the division, you find:

x = 3.

Thus, the second term of the proportion is indeed 3. This illustrates the relationships between the numbers in a proportion, where finding one element allows us to calculate others proportional to it.