Tip: Let's assume this is a right angled triangle with height \(5\). How can we use the ratio \(BX:XA=4:1\) to calculate the ratio \(BY:YA\)?
Tip: Let's assume the base is \(1\) unit wide. How can we use this to calculate the area with height \(XA\)?
Tip: As the ratio links proportionally to the height of the triangle, so does the width.
