Let G be the center of equilateral triangle XYZ. A dilation centered at G with scale factor -2/3 is applied to triangle XYZ to obtain triangle X'Y'Z'. Let A be the area of the region that is contained in both triangles XYZ and X'Y'Z'. Find A/[XYZ].
We had that question a few times already; here's a link:
https://web2.0calc.com/questions/help_54234#r3