The measure of GCB is 48 degrees
The complete question is added as an attachment.
From the attachment, we have:
GCB = FCG
So, we have
13x - 9 = 9x + 3
Evaluate the like terms
4x = 12
Divide by 4
x = 3
Substitute x = 3 in GCB= 13x+9
GCB= 13 * 3 + 9
Evaluate
GCB= 48
Hence, the measure of GCB is 48 degrees
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