-l0 = -2+1/2 d solved for d
\(-10 =-2+ \dfrac{1}{2} d\) \(-10=-2+ \dfrac{d}{2}\) \(-10= \dfrac{d}{2} -2\) \(Regroup \ terms\) \(-10+2= \dfrac{d}{2}\) \(Add \ 2 \ to \ both \ sides\) \(-8= \dfrac{d}{2}\) \(-8*2=d\) \(Multiply \ both \ sides \ by \ 2\) \(d=-16\)