Problems 25 and 26: a) Simplify: 1/5 + 3/5 + 2/5. b) Arrange 2/3, 5/12, 1/8 in ascending order. c) Study the bill table and complete it.

The simplified expression is $\boxed{\frac{6}{5}}$.

b) Arrange $\frac{2}{3}$, $\frac{5}{12}$ and $\frac{1}{8}$ in ascending order.

The LCM of 3, 12, and 8 is 24.

The numerators are 16, 10, and 3.
In ascending order, they are 3, 10, 16.
So, the fractions in ascending order are $\frac{3}{24}, \frac{10}{24}, \frac{16}{24}$.

The fractions in ascending order are $\boxed{\frac{1}{8}, \frac{5}{12}, \frac{2}{3}}$.

:
Study the bill table below and complete it correctly.

a) Complete the table.

Quantity = $3 \text{ kg}$
Unit Cost = $\text{sh } 4200 \text{ per kg}$
Amount = Quantity $\times$ Unit Cost = $3 \text{ kg} \times \text{sh } 4200/\text{kg} = \text{sh } 12600$.

Unit Cost = $\text{sh } 4900 \text{ per kg}$
Amount = $\text{sh } 9800$
Quantity = Amount / Unit Cost = $\text{sh } 9800 / (\text{sh } 4900/\text{kg}) = 2 \text{ kg}$.

Quantity = $500 \text{ gm} = 0.5 \text{ kg}$
Amount = $\text{sh } 800$
Unit Cost = Amount / Quantity = $\text{sh } 800 / 0.5 \text{ kg} = \text{sh } 1600 \text{ per kg}$.

Total Amount = Amount (Sugar) + Amount (Rice) + Amount (Salt)
Total Amount = $\text{sh } 12600 + \text{sh } 9800 + \text{sh } 800 = \text{sh } 23200$.

The completed table is:

b) If Joseph was given a discount of sh 400, how much did he pay?

Total Amount = $\text{sh } 23200$
Discount = $\text{sh } 400$

Amount Paid = Total Amount - Discount
Amount Paid = $\text{sh } 23200 - \text{sh } 400 = \text{sh } 22800$.
Joseph paid $\boxed{\text{sh } 22800}$.