Noo solve the problem in English NOT KISWAHILI

Here is the solution to (a) in English:

1. (a) An arithmetic sequence is composed of numbers exactly divisible by 4, with the last number being 928. The first number is 4.

• Step 1: Determine the common difference. Since all numbers in the sequence are exactly divisible by 4, the common difference between consecutive numbers must be 4.

  $$d = 4$$

  The common difference is $\boxed{\text{4}}$.

• Step 2: Determine the number of terms in the series. We use the formula for the $n$-th term in an arithmetic sequence: $L = a + (n-1)d$. We have $L = 928$, $a = 4$, and $d = 4$.

  $$\begin{align*} 928 &= 4 + (n-1)4 \\ 928 - 4 &= (n-1)4 \\ 924 &= 4(n-1) \\ \frac{924}{4} &= n-1 \\ 231 &= n-1 \\ n &= 231 + 1 \\ n &= 232 \end{align*}$$

  The number of terms in the series is $\boxed{\text{232}}$.

• Step 3: Determine the sum of all terms. We use the formula for the sum of an arithmetic series: $S_n = \frac{n}{2}(a + L)$. We have $n = 232$, $a = 4$, and $L = 928$.

  $$\begin{align*} S_{232} &= \frac{232}{2}(4 + 928) \\ S_{232} &= 116(932) \\ S_{232} &= 108112 \end{align*}$$

  The sum of all terms is $\boxed{\text{108,112}}$.

• Step 4: Determine the 80th term. We use the formula for the $n$-th term: $a_n = a + (n-1)d$. We want to find the 80th term, so $n = 80$. We have $a = 4$ and $d = 4$.

  $$\begin{align*} a_{80} &= 4 + (80-1)4 \\ a_{80} &= 4 + (79)4 \\ a_{80} &= 4 + 316 \\ a_{80} &= 320 \end{align*}$$

  The 80th term is $\boxed{\text{320}}$.