To make these chocolate crispies I used:
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.
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.
source:mathisfun.com
point of view:
since i'm in 5th grade, i haven't studied this yet but since i went to MTAP when i was in 4th grade (MTAP is a contest for all the students that are good in math) i had to study this earlier. finding the ratio is pretty easy once you understand it properly. you will enjoy it. try to apply it in your life. for example:
there are 45 students in my class and 25 of them are girls while the other 20 are boys : the ratio is 25:20 but you can still simplify that. since their greatest common factor is 5, the ratio is 5:4 .
meena