Answer
$\dfrac{-71}{150}$
Work Step by Step
Factor each denominator completely to obtain:
$15=3(5)
\\50=2(25) = 2(5)(5)$
Thus, the least common multiple of the two numbers is: $2(3)(5)(5)=150$
This means that the LCD is also $150$.
The fractions are not similar since they have different fractions.
Make the fractions similar using their LCD of $150$.
$\dfrac{1}{15} - \dfrac{27}{50}
\\= \dfrac{1\color{blue}{(10)}}{15\color{blue}{(10)}}-\dfrac{27\color{blue}{(3)}}{50\color{blue}{(3)}}
\\=\dfrac{10}{150}-\dfrac{81}{150}$
Now that the fractions are similar, subtract the numerators and copy the denominator to obtain:
$=\dfrac{10-81}{150}
\\=\dfrac{-71}{150}$
