Using proportions, that is, finding 25% of 12 km, it is found that she has already biked 3 km on Tuesday.
A proportion is a fraction of a total amount.
In this problem, she has already biked 25% out of her goal of 12 km, hence the distance that she has biked is given by:
d = 0.25 x 12 = 1/4 x 12 = 3 km.
More can be learned about proportions at https://brainly.com/question/24372153
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