Answer: d=4
Explanation:
you need to move the two variable with d on one side and the number without d to the other. When you do so you get
16=4d
Because you need to subtract the 5 d from the 9d then to isolate d you need to divide the four by itself and because what you do to one side you have to do to the other you also have to divide the 16 by 4
Which is how you get
D=4
I hope this helps!!