$5n+40=2\left( n-1 \right)$
Distribute $2$ through the parentheses$5n+40=2n-2$
Move the variable to the left-hand side and change its sign$5n+40-2n=-2$
Move the constant to the right-hand side and change its sign$5n-2n=-2-40$
Collect like terms$3n=-2-40$
Calculate the difference$3n=-42$
Divide both sides of the equation by $3$$n=-14$