Answer:
addition
Step-by-step explanation:
18 ( d - 9 ) = 198
3
divide both side by 18
d - 9 = 198
3 18
d - 9 = 11
3
multiply both sides by 3
d - 27 = 33
add 27 to both sides
d = 33 + 27
lastly, add them together
d = 60
therefore, the last step is addition
