2/5-11/18

Let's evaluate: $\frac{2}{5}-\frac{11}{18}$

ⓘ Add fractions by using a common denominator and then adding their numerators. We choose $90$, the least common multiple of $5$ and $18$. Multiplying the numerator and the denominator by the same number does not change the fraction: $\frac{2}{5}-\frac{11}{18}$ = $\frac{2\times 18}{5\times 18}-\frac{11\times 5}{18\times 5}$ = $\frac{2\times 18-11\times 5}{5\times 18}$

$\frac{2\times 18-11\times 5}{5\times 18}$

ⓘ Multiplications are done before additions and subtractions: $2\times 18$ = $2\times (10+8)$ = $2\times 10+2\times 8$ = $20+16$ = $36$, $11\times 5$ = $(10+1)\times 5$ = $10\times 5+5$ = $50+5$ = $55$

ⅰ $5\times 18$ = $5\times (10+8)$ = $5\times 10+5\times 8$ = $50+40$ = $90$

$\frac{36-55}{90}$

ⓘ The numerator and the denominator are computed before the division: $36-55$ = $-19$

▶Result:   $-\frac{19}{90}$

The numeric value of: $-\frac{19}{90}$ is:

▷ $\approx -0.2111$