Prices are: £40 per guest. Total cost reduced by 5% with over 60 guests.
First, we work out the cost of Nisha's suggestion.
£40 x 70 guests = 2800
To find 5% of this, we can divide by 10 to get 10% (280), and then divide by 2 to get 5% (140). Then we do £2800-£140=£2660.
Next we work out Dipen's cost.
To reduce our total guests by one fifth, we first divide 70 by 5 to get 14. Then take 14 away from 70 to get 56. To find the cost of inviting 56 guests, we multiply 56 by £40 which gives us £2240.
Is this £500 less than Nisha's costs?
£2660-£2240=£420 so the answer is no, they would only save £420.