Решите уравнение №516

Решите задачу:

$1) \ (\frac{13}{12}+ 3\frac{3}{4})+x=4 \frac{1}{2} \\ \\ \frac{13}{12}+ \frac{15}{4}+x=\frac{9}{2} \\ \\ x = \frac{9}{2}-\frac{13}{12}-\frac{15}{4}=\frac{54-13-45}{12}=\frac{-4}{12}=-\frac{1}{3} \\ \\ 3) \ x-(\frac{68}{9}-\frac{31}{6})=-3 \frac{1}{2} \\ \\ x-\frac{68}{9}+\frac{31}{6}=-\frac{7}{2} \\ \\ x=-\frac{7}{2} +\frac{68}{9} -\frac{31}{6}=\frac{-63+136-93}{18}=\frac{-20}{18}=-\frac{10}{9}=-1\frac{1}{9}$