Ratio - Make Some Chocolate Crispies

To make these chocolate crispies I used:

20 g (grams) of chocolate
15 g of cornflakes or similar

This made 1 cake. Recipe Here

Your mathematics task is to:

1) calculate the ratio of chocolate to cornflakes, and then:

2) work out the amount of ingredients to make 21 cakes.

1) We can see that the ratio of chocolate to cornflakes is 20:15

But this can be simplified further. The Greatest Common Factor is 5, so:

If we have 20 parts chocolate to 15 parts cornflake, divide each side by 5 and we get 4:3

This is the ratio of chocolate to cornflakes.

2) We need to work out how much chocolate and cornflakes we need to make 21 cakes.

The recipe is for 1 cake but we want 21, so multiply both ingredients by (21 cakes / 1 cake), or simply by 21:

21×20 = 420
21×15 = 315

So to make our 21 cakes we need:

420 g of chocolate
315 g of cornflakes

Question: If we only had 400g of chocolate, how many cakes could we make, and what quantity of cornflakes would we need?