Solve for: n+[ n (1 /(1) 2) ]+(n+1.40) = 3.50

Expression: $$n + [ n ( 1 \frac { 1 } { 2 } ) ] + ( n + 1.40 ) = 3.50$$

Multiply both sides of the equation by $2$.

$$2n+n\left(1\times 2+1\right)+2n+2.8=7$$

Multiply $1$ and $2$ to get $2$.

$$2n+n\left(2+1\right)+2n+2.8=7$$

Add $2$ and $1$ to get $3$.

$$2n+n\times 3+2n+2.8=7$$

Combine $2n$ and $n\times 3$ to get $5n$.

$$5n+2n+2.8=7$$

Combine $5n$ and $2n$ to get $7n$.

$$7n+2.8=7$$

Subtract $2.8$ from both sides.

$$7n=7-2.8$$

Subtract $2.8$ from $7$ to get $4.2$.

$$7n=4.2$$

Divide both sides by $7$.

$$n=\frac{4.2}{7}$$

Expand $\frac{4.2}{7}$ by multiplying both numerator and the denominator by $10$.

$$n=\frac{42}{70}$$

Reduce the fraction $\frac{42}{70}$ to lowest terms by extracting and canceling out $14$.

$$n=\frac{3}{5}$$