To solve this question, you need to put the 2/3x into the f(x). Remember that x^-1 equal to 1/x
Assuming 2/3x is 2/3 *x , the calculation would be:
f(x)=x^-1
f(2/3x)=(2/3*x)^-1.
f(2/3x)=1/ (2x/3)
f(2/3x)=3/(2x)
Assuming 2/3x is 2/(3x) , the calculation would be:
f(x)=x^-1
f(2/3x)=(2/3x)^-1.
f(2/3x)=1/ (2/3x)
f(2/3x)=3x/2