$$\left(n-4\right)\times 2=8\left(n+4\right)$$
Use the distributive property to multiply $n-4$ by $2$.$$2n-8=8\left(n+4\right)$$
Use the distributive property to multiply $8$ by $n+4$.$$2n-8=8n+32$$
Subtract $8n$ from both sides.$$2n-8-8n=32$$
Combine $2n$ and $-8n$ to get $-6n$.$$-6n-8=32$$
Add $8$ to both sides.$$-6n=32+8$$
Add $32$ and $8$ to get $40$.$$-6n=40$$
Divide both sides by $-6$.$$n=\frac{40}{-6}$$
Reduce the fraction $\frac{40}{-6}$ to lowest terms by extracting and canceling out $2$.$$n=-\frac{20}{3}$$