For this case, the first thing we must do is define variables.
We have then:
t: cost of the torch
b: cost of the battery
The cost of both items in £ is given by:
Therefore, we have the following equation:
Then, we know that:
The torch costs eleven times as much as the battery.
Substituting equation two in the equation we have:
Clearing the value of b we have:
Answer:
The cost of the battery is 0.43 £
