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Work Shown:
Solve the second equation for f(b)
2f(b) = 28
f(b) = 28/2
f(b) = 14
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Plug in x = b and solve for b
f(x) = 3x-1
f(b) = 3b-1 ... replace every x with b
14 = 3b-1 ..... plug in f(b) = 14
3b-1 = 14
3b = 14+1
3b = 15
b = 15/3
b = 5
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f(x) = 3x-1
f(2b) = 3(2b)-1 .... replace every x with 2b
f(2b) = 3(2*5)-1 .... plug in b = 5
f(2b) = 3*10-1
f(2b) = 30-1
f(2b) = 29
