Make r the subject of the relation y = 5/r - 1 and find the value of r when y = -1 and x = 19. A woman bought 240 tubers of yams for GHc 60.00. She sold all of them at 3 for GHc20.00. Find her percentage profit.

$$y(r+1) = r-1$$ $$yr + y = r-1$$

$$r = \frac{-(1+y)}{y-1}$$ $$r = \frac{1+y}{1-y}$$

The expression for $r$ is $\boxed{r = \frac{1+y}{1-y}}$.

Substitute $y=1$ into the expression for $r$.

$$r = \frac{1+1}{1-1} = \frac{2}{0}$$

Division by zero is undefined. Therefore, there is no value of r for which $y=1$.
The value of $r$ when $y=1$ is $\boxed{\text{undefined}}$.

$$\text{Profit/Loss} = \text{Total Selling Price} - \text{Cost Price}$$ $$\text{Profit/Loss} = \text{GH¢}960.00 - \text{GH¢}1200.00 = -\text{GH¢}240.00$$

Since the result is negative, the woman incurred a loss of GH¢240.00.

$$\text{Percentage Profit} = \frac{\text{Profit/Loss}}{\text{Cost Price}} \times 100\%$$ $$\text{Percentage Profit} = \frac{-\text{GH¢}240.00}{\text{GH¢}1200.00} \times 100\% = -0.2 \times 100\% = -20\%$$

The woman made a \boxed{\text{20% loss}}.