STEP 1) times 18m by 12m which equals 216m2 (when you times metres by metres it makes metres squared (mxmxm=m3 etc.))
STEP 2) 216m2 times 2.1 which equals 453.60 (we times 216 by 2.1 because it's basically saying 216 (metres squared) times 2.1 dirhams per square metre.)
i hope this helped, (sorry if i was kind of confusing) :)))
