The problem asks for the sum of the first 8 terms of an arithmetic sequence with the following terms:
$16, 20, 25, \dots$

Step-by-Step Solution:

1. Identify the parameters of the arithmetic sequence:

   • First term $a = 16$
   • Common difference $d = 20 - 16 = 4$

2. Find the sum of the first $n$ terms of an arithmetic sequence:
   The formula for the sum of $n$ terms ($S_n$) is:
   $S_n = \frac{n}{2} \times (2a + (n-1)d)$
   Here:

   • $n = 8$ (the number of terms)
   • $a = 16$ (the first term)
   • $d = 4$ (common difference)

3. Substitute the values into the formula:
   $S_8 = \frac{8}{2} \times [2(16) + (8-1)(4)]$
   Simplify step by step:

   • $\frac{8}{2} = 4$
   • $2(16) = 32$
   • $(8-1)(4) = 7 \times 4 = 28$
     Therefore:
     $S_8 = 4 \times (32 + 28)$
   • $32 + 28 = 60$
     So:
     $S_8 = 4 \times 60 = 240$

Final Answer:

The sum of the first 8 terms is 240.

Would you like me to explain another part of this calculation, or do you need help with a similar problem?

Related Questions:

1. What is the general formula for the $n$-th term of an arithmetic sequence?
2. How do you find the common difference in an arithmetic sequence?
3. What is the sum of the first 10 terms of the series $16, 20, 25, \dots$?
4. How can you determine the number of terms in an arithmetic sequence if given a specific sum?
5. What is the difference between arithmetic and geometric sequences?

Tip: In arithmetic sequences, always check the first term and common difference before using the formula for sums or terms.