How many people will be needed to erect the fence in 4 days? 2.2. If one person rates R70/hour. How much will be the total cost of labourers in 3 days if 3 people work for 8 hours a day?

The work required to erect the fence is constant. It is calculated as the number of people multiplied by the number of days.

$$\text{Total work} = \text{People} \times \text{Days}$$ $$\text{Total work} = 14\, \text{people} \times 8\, \text{days}$$ $$\text{Total work} = 112\, \text{person-days}$$

To complete the same amount of work in 4 days, we divide the total work by the new number of days.

$$\text{Number of people} = \frac{\text{Total work}}{\text{New number of days}}$$ $$\text{Number of people} = \frac{112\, \text{person-days}}{4\, \text{days}}$$ $$\text{Number of people} = 28\, \text{people}$$

To erect the fence in 4 days, 28 people will be needed.

$$\boxed{\text{28 people}}$$

One person works for 8 hours a day for 3 days.

$$\text{Hours per person} = 8\, \text{hours/day} \times 3\, \text{days}$$ $$\text{Hours per person} = 24\, \text{hours}$$

There are 3 people working.

$$\text{Total hours worked} = \text{Hours per person} \times \text{Number of people}$$ $$\text{Total hours worked} = 24\, \text{hours} \times 3$$ $$\text{Total hours worked} = 72\, \text{hours}$$

Each person rates R70 per hour.

$$\text{Total cost} = \text{Total hours worked} \times \text{Rate per hour}$$ $$\text{Total cost} = 72\, \text{hours} \times \text{R}70/\text{hour}$$ $$\text{Total cost} = \text{R}5040$$

The total cost of labourers will be R5040.

$$\boxed{\text{R}5040}$$