IMSO 2019 — Math Division — Essay Question 8

In the diagram below, $ABCD$ is a trapezium and $E$ is the midpoint of $DC$. The areas of the triangles $ABG$, $ABF$ and $AGE$ are 15 cm², 45 cm² and 60 cm², respectively. What is the area, in cm², of the trapezium $ABCD$?