[tex]\it b)\ \ =1\dfrac{1}{4}+2\dfrac{1}{4}=3\dfrac{1}{2}\\ \\ \\ c)\ \ =2\dfrac{2}{3}-1\dfrac{1}{3}=1\dfrac{1}{3}\\ \\ \\ d)\ \ =\dfrac{17-19}{6}=-\dfrac{\ 2^{(2}}{6}=-\dfrac{1}{3}\\ \\ \rule{130}{0.9}\\ \\ \\ d)\ \ =-\dfrac{6}{7}+\dfrac{5}{7}=-\dfrac{1}{7}[/tex]
