[tex]\dfrac{2}{5}n+\dfrac{1}{10}=\dfrac{1}{2}(n+4)\ \ \ |\text{change the fractions in decimal}\\\\\dfrac{2\cdot2}{5\cdot2}n+0.1=0.5(n+4)\ \ \ \ |\text{use distributive property}\\\\\dfrac{4}{10}n+0.1=0.5n+0.5\cdot4\\\\0.4n+0.1=0.5n+2\ \ \ \ |-0.1\\\\0.4n=0.5n+1.9\ \ \ \ |-0.5n\\\\-0.1n=1.9\ \ \ \ |\cdot(-10)\\\\n=-19[/tex]
