Answer:
20in^2
Step-by-step explanation:
Since you multiply the original area of the triangle by the scale factor to get the new area, you can find the original area (before dilation) by dividing the dilated triangle's area by the scale factor. Since 100 is the area of the dilated triangle, and 5 is your scale factor, you do 100/5 to get the area of the triangle before it was dilated.
