Incomplete question: we assume figures to explain further
Answer and explanation:
Given that client pays $0.15/kwh
If old fridge is inefficient and consumes 120kwh/month
And new fridge is efficient and therefore consumes 50kwh/month
For the old fridge, client will be paying
120×0.15= $18 per month on electricity charges
For the new fridge, client will be paying
50×0.15= $7.5 per month on electricity charges