Question 1096757
To get from {{{4x}}} to {{{(1/2)x}}}, divide by 8. 
Then subtract 1 from that.
{{{g(x)=f(x)/8-1}}}
To verify, plug in and check,
{{{(1/2)x-1=(4x)/8-1}}}
{{{x/2-1=x/2-1}}}
True, so correct.
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Your g(x) is incomplete.