Mathematics
OpenStudy (anonymous):

So, let's start at the beginning. $$2(n + 1.5) = 4.5$$ You can distribute the 2: \begin{align} 2n + 2 \cdot (1.5) &= 4.5\\ 2n + 3 &= 4.5\\ \end{align} Can you see how that does not lead to $$2n = 6$$, and therefore your final answer isn't right?