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MathNet 2019-part-04 — 184 problems (EN–VI) Question 57

Math Olympiad Vault · MathNet 2019-part-04 — 184 problems (EN–VI)

Question 57

Given is the triangle $ABC$. A line from point $A$ intersects the side $BC$ in $D$. Parallel to $BC$ we draw four lines such that they divide $AB$ and $AC$ in five equal parts. From the ten pieces in which the triangle $ABC$ is divided, the two dotted ones have the same area. Also, the area of the grey triangle at the bottom left next to $A$ is $5$. What is the area of the grey quadrilateral at the upper right next to $C$?

Question illustration

A) $50$ B) $81$ C) $100$ D) $119$ E) $121$