Question

Circle is divided into 20 equal parts. What is the angle measure of three of those parts?

Answer 1

First, imagine a circle divided into 4 quarters
than you may use the following proportion

angle measure ------- part of circle
$90^0 - -----\frac14\\ x \ \ ------\frac3{20}\\ \\ \frac14x=90^0\cdot\frac3{20}\\ \frac14x=\frac{270}{20}\\ \frac14x=\frac{27}2\ \ \ \ |\cdot4\\ x=\frac{27}2\cdot4\\ x=\frac{108}2\\ \boxed{x=54\ degrees}$