Answer:
, Option B
Step-by-step explanation:
Given, 
Formula needed,

Therefore,






Option B is correct.
9514 1404 393
Answer:
216 mi/h
Step-by-step explanation:
The time for the trip with the wind is ...
(1080 mi)/(225 +45 mi/h) = 4 h
The time for the trip against the wind is ...
(1080 mi)/(225 -45 mi/h) = 6 h
The average speed for the entire round trip is ...
(2160 mi)/(4 +6 h) = 216 mi/h
I assume that you meant RS and ST are segments of RT. If that is true then:
RS+ST=RT, using the values for these given...
8y+4+4y+8=36 combine like terms on left side
12y+12=36 subtract 12 from both sides
12y=24 divide both sides by 12
y=2