Answer:
im not sure if the +2-4 is also part of the exponent but
if its 5(2/3)^(x+2-4) with everything after x being in the exponent, the horizontal asymptote is
y = 0
if it is 5(2/3)^x + 2 - 4 with the +2 - 4 not being part of the exponent, the horizontal asymptote is
y = -4