Answer:
$0.75 per lemon
Explanation:
This question is an example of price per unit. To work this out you would simply divide the price of $3 by the quantity of 4, which gives you 0.75. This is because the question states that the price of 4 is $3, and so to find the price of 1 you would divide the price by the quantity.
price per unit

1) Divide 3 by 4.

working backwards:
To double check your answer you could multiply the price per unit by 4, and if the answer is 3 then the price per unit is correct.
1) Multiply 0.75 by 4.
