Answer:
200 mph
Step-by-step explanation:
Ⓗⓘ ⓣⓗⓔⓡⓔ
Plane a: 400mph
Plane b: x mph
2x=400
x=200
(っ◔◡◔)っ ♥ Hope this helped! Have a great day! :) ♥
BTW, brainliest would be greatly appreciated, I only need one more before I advance, thanks!
Also, I may have done something wrong, please tell me if it's incorrect!
Step-by-step explanation:

I remember CUP -- concave up positive. Here we have a leading coefficient that's negative, so the cup is upside down, the parabola opens down, an arch not a bowl.
The picture is upside down my dude, delete the question, re-upload it and ill help you out.
<span>The rate is the ratio and the unit rate is the rate when the denominator is 1.
$279 for 9 tickets.
=> rate = $279 / 9 tickets => unit rate = $ 31/ ticket
$18 for 6 volleyballs.
=> rate = $ 18 / 6 volleyballs => unit rate = $ 3 / volleyball
4 fouls in 20 minutes.
=> rate = 4 fouls / 20 minutes => unit rate = 0.2 fouls / minute
36 strikeouts in 54 innings.
=> rate = 36 strikeouts / 54 innings => unit rate = 0.67 strikeouts / inning
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