Follow Order of Operations rules (PEMDAS): multiplication before addition and subtraction.
First, apply the distributive property of mult. to 6.5(2d - 3):
13d - 19.5
Then we have 8.5 = 13d - 19.5 + d.
Combining like terms, we get 14d = 8.5 + 19.5, or 14d = 28. Thus, d = 2.
