Answer:
7:12
Explanation:
21 and 36 are both multiples of 3.
3 times 7 is 21, and 3 times 12 is 36.
Now, this ratio becomes: 3 x 7 : 3 x 12
Dividing by 3 on both sides,, we have: 7:12. The ratio 7:12 can't be simplified further, so that's the answer.
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