Answer:
a
Step-by-step explanation:
Let's break this down:
let's join together all the elements we have on each side.
left side: sum all the numbers with the constact d (9-4-2=3)
can we sum anything help on this side? there is nothing left so it's done
right side= -3d is alone, leave it for now
at this point we have 3d+8=-3d which is equal to option a
