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B Beacuse b best fits the suituation
Given -:
EF = 2X-7
FG = 4X-20
EG = 21
FIND OUT
EF =?
FG = ?
To proof
as given in the question
we have the value of EF = 2X-7 , FG = 4X-20 and EG = 21
Thus we have
EG = EF + FG
21 = 2X-7 + 4X- 20
21 = 6x - 27
48 = 6x
x = 8
Hence proved
Now put this value

Now

Hence proved
Bidmas, division before addition3x(3+12/3)-4 = 3x(3+4)-4 = 21-4 = 17
Angle four is 22 degrees because dune side interior angles are supplementary