1. **State the problem:** We are given that the number of states that joined the United States between 1776 and 1849 is twice the number of states that joined between 1850 and 1900. 2. **Define variables:** Let $x$ be the number of states that joined between 1850 and 1900. 3. **Translate the problem into an equation:** The number of states between 1776 and 1849 is 30, and it is twice the number of states between 1850 and 1900. So, we write: $$30 = 2x$$ 4. **Check the options:** - Option A: $30x = 2$ (Incorrect, this implies multiplication, not twice) - Option B: $2x = 30$ (Correct, matches our equation) - Option C: $\frac{x}{2} = 30$ (Incorrect, this implies half of $x$ equals 30) - Option D: $x + 30 = 2$ (Incorrect, sum equals 2 is not correct) **Final answer:** The correct equation is **$2x = 30$**.