Question

Will MARK brainliest

Answer 1

Answer:

  see below

Step-by-step explanation:

Since your proof wants to show the slopes of AC and DF are equal using substitution, you want to show the ratios that define those slopes are equal. Those ratios are BC/AB and EF/DE. So, the missing step is the one saying those ratios are equal:

  BC/AB = EF/DE