Answer
$11\dfrac{3}{5}$
Work Step by Step
Note that $18 = 17+1 = 17+\dfrac{5}{5} = 17\dfrac{5}{5}$.
Thus, the given expression is equivalent to
$=17\dfrac{5}{5} - 6\dfrac{2}{5}$
Subtract the whole number parts and the fraction parts to obtain:
$\\(17-6) + (\dfrac{5}{5}-\dfrac{2}{5})
\\=11+\dfrac{3}{5}
\\=11\dfrac{3}{5}$
