Answer :

log(1/216)^(x+2) = log 6^12

(x+2) log(1/216) = log 6^12

xlog(1/216) + 2log(1/216) = log6^12

xlog(1/216) = log6^12 - 2log(1/216)

x = [log6^12-2log(1/216] / log(1/216)

x = -6