\(\left(-\dfrac{1}{4}\right)-\dfrac{9}{4}:\left(\dfrac{5}{4}+\dfrac{1}{10}\right)\)
\(=\left(-\dfrac{1}{4}\right)-\dfrac{9}{4}:\dfrac{27}{20}\)
\(=\left(-\dfrac{1}{4}\right)-\dfrac{5}{3}\)
\(=-\dfrac{23}{12}\)
= (-1/4) - 9/4 : 27/20
= (-1/4) - 5/3
= -23/12