profit = selling price - cost price
Let
the cost price for each apple = $1
The cost of 18 apple = $18
Remember the cost price of 18 apples is the same as the selling price of 16 apples. Therefore,
16 apples will cost $16 and selling 16 apples is same as the cost of 18 apple($18). This means the profit will be
profit = 18 - 16 = $2