1. **State the problem:** We have a sequence where each term is obtained by adding 4 to the previous term and then dividing by 2. 2. **Given terms:** The sequence is $a_1, 6, 5, 4.5, \ldots$ and we need to find the first term $a_1$. 3. **Use the rule backward:** The rule is $a_{n+1} = \frac{a_n + 4}{2}$. 4. **Find $a_1$ using $a_2 = 6$:** $$6 = \frac{a_1 + 4}{2}$$ Multiply both sides by 2: $$12 = a_1 + 4$$ Subtract 4 from both sides: $$a_1 = 12 - 4 = 8$$ 5. **Verify with next terms:** Calculate $a_3$ from $a_2 = 6$: $$a_3 = \frac{6 + 4}{2} = \frac{10}{2} = 5$$ Calculate $a_4$ from $a_3 = 5$: $$a_4 = \frac{5 + 4}{2} = \frac{9}{2} = 4.5$$ These match the given sequence. **Final answer:** The first term $a_1$ is $8$.