1) Let's solve for d, this expression
6-4d=16-9d Subtract 6 from both sides to isolate the d term
6-6-4d=16-6-9d
-4d=10 -9d Add 9d to both sides
9d -4d = 10 -9d +9d
5d = 10 Divide both sides by 5
d= 2
