Hey I'm on this question on my test too. I think the answer is:
First Box: "Reflection across the x-axis" Last Box: "Translation 1 unit down"
What the sentence should look like = "<span>△RST</span><span> to </span><span>△<span>R′</span><span>S′</span><span>T′</span></span><span> is a reflection across the x-axis followed by a translation 1 unit down."