Answer:
3:4
4:5
Step-by-step explanation:
The ratios are ...
short side : long side = 12 : 16 = 3 : 4
and for the other rectangle, ...
short side : long side = 8 : 10 = 4 : 5
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To reduce the ratio to lowest terms, divide each number by their greatest common factor. 12 and 16 have a common factor of 4: 12=4·3, 16=4·4. 8 and 10 have a greatest common factor of 2.