Problem
A shop sells bottles of orange juice for $£ 1.60$, but will take $20 \%$ off the total cost when you buy more than 20 bottles. How much does it cost, in pounds $(£)$, to buy 40 bottles of orange juice?
Solution
Step 1 ：Calculate the cost of buying 40 bottles without any discount: \(40 \times 1.6 = 64\)
Step 2 ：Apply the 20% discount to the total cost: \(64 \times (1 - 0.2) = 51.2\)
Step 3 ：\boxed{51.20}
