Question

If one in every five sweets is a toffee what proportion is chocolate?

Answer 1

I'd guess 4/5 because 5 - 1 = 4. That's assuming that the chocolate is the remainder. 

Answer 2

I would also say the answer is 4/5. Chocolate is 4/5 because 1/5 is toffee. 1/5 + 4/5 = 5/5 or all sweets(chocolate and toffee).