Given, a = 7/-11, b = -2/5 and c = -3/22

=> a = -7/11, b = -2/5 and c = -3/22

LHS: (a + b) + c

      a + b = -7/11 + (-2/5)

=> a + b = -7/11 - 2/5

=> a + b = (-7 * 5 - 2 * 11)/55                  {LCM(11, 5) = 55}

=> a + b = (-35 - 22)/55

=> a + b = -57/55

Now, (a + b) + c = -57/55 + (-3/22)

                           = -57/55 - 3/22

                           = (-57 * 2 - 3 * 5)/110         {LCM(55, 22) = 110}

                           = (-114 - 15)/110

                           = -129/110

RHS: a + (b + c)

b + c = (-2/5) + (-3/22)

        = -2/5 - 3/22

        = (-2 * 22 - 3 * 5)/110

        = (-44 - 15)/110

        = -59/110

Now, a + (b + c) = -7/11 + (-59/110)

                          = -7/11 - 59/110

                          = (-7 * 10 - 59 * 1)/110

                          = (-70 - 59)/110

                          = -129/110

So, (a + b) + c = a + (b + c) = -129/110