Answer: Let's assume the cost of 1 kilogram of bananas is represented by 'x'.
According to the given information, 4.5 kg of bananas and 3.5 kg of apples together cost £6.75. We also know that the cost of 1 kg of apples is £5.40.
Using this information, we can set up the following equation:
4.5x + 3.5(£5.40) = £6.75
Now let's solve for 'x':
4.5x + 3.5(£5.40) = £6.75
4.5x + £18.90 = £6.75
4.5x = £6.75 - £18.90
4.5x = -£12.15
x = (-£12.15) / 4.5
x ≈ -£2.70
The cost of 1 kilogram of bananas, based on this calculation, is approximately -£2.70. However, it's important to note that a negative cost doesn't make sense in this context. It's possible there may be an error in the given information or the setup of the equation.