回答
What about 〜？は、〜はどうなの？ 〜はどうなったの？という問いです。
ですので、〜がどうなのか、〜はどうなったのか、ということについて答えることになります。
A: Tomo got the job.
B: Well, I'm happy for Tomo, but what about Hiro..?
A: HIro didn't get the job.
B: That sucks. He was trying really hard, you know.
Andy: What's your opinion about this, Tomo?
Tomo: I think it's good.
Andy: What about you, Hiro?
Hiro: I don't think it's a good idea.
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How about 〜？というたずね方もあります。これは、〜はいかが？という聞き方ですので、それにたいして「いいね」とか「気が進まない」とかいうふうに答えます。
A: There are so many choices... I don't know which one to pick...
B: How about lobster salad?
A: Oh, I can't eat seafood.
B: Oh OK, so how about... grilled chicken sandwich? It's pretty good.
A: That's a good choice. I'll go for that.
Andy: Hey folks, how about going out tonight?
Tomo: Yeah I'm in, what about you, Hiro?
Hiro: No, I got to do my assingment tonight.