4 = -0.8n
To find n divide both sides by -0.8:
n = 4 / -0.8
n = -5
n = - 5
consider the rational form of - 0.8 = - [tex]\frac{8}{10}[/tex] = - [tex]\frac{4}{5}[/tex]
Then 4 = - [tex]\frac{4n}{5}[/tex]
multiply both sides by 5
20 = - 4n
divide both sides by - 4
n = - [tex]\frac{20}{4}[/tex] = - 5