1. **State the problem:** We need to find the sum of 58 and 6, i.e., calculate $58 + 6$. 2. **Formula used:** Addition of two numbers is given by $$a + b = c$$ where $a$ and $b$ are the addends and $c$ is the sum. 3. **Calculate the sum:** $$58 + 6 = 64$$ 4. **Answer the question:** The sum of 58 and 6 is 64. 5. **Complete the missing number in the second equation:** Given $$60 + \_ = 64$$, subtract 60 from both sides: $$\cancel{60} + x = 64 \Rightarrow x = 64 - \cancel{60} = 4$$ 6. **Final answers:** - $58 + 6 = 64$ - $60 + 4 = 64$