Using proportions, the missing side length in the image below is of 20.
What is a proportion?
A proportion is a fraction of a total amount, and the measures are related using a rule of three. Due to this, relations between variables, either direct or inverse proportional, can be built to find the desired measures in the problem.
In this problem, the side lengths are proportional, being related by the rule of three given as follows:
x/10 = 14/7
Applying cross multiplication:
7x = 14 x 10
7x = 140
x = 140/7
x = 20.
More can be learned about proportions at https://brainly.com/question/24372153
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