Add all the A tasks

Task/Arithmetic-Complex/Ruby/arithmetic-complex-1.rb

@@ -0,0 +1,14 @@
+require 'complex'  # With Ruby 1.9, this line is optional.
+
+# Two ways to write complex numbers:
+a = Complex(1, 1)       # 1. call Kernel#Complex
+i = Complex::I          # 2. use Complex::I
+b = 3.14159 + 1.25 * i
+
+# Operations:
+puts a + b              # addition
+puts a * b              # multiplication
+puts -a                 # negation
+puts 1.quo a            # multiplicative inverse
+puts a.conjugate        # complex conjugate
+puts a.conj             # alias for complex conjugate

Task/Arithmetic-Complex/Ruby/arithmetic-complex-2.rb

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+# Other ways to find the multiplicative inverse:
+puts 1.quo a            # always works
+puts 1.0 / a            # works, but forces floating-point math
+puts 1 / a              # might truncate to integer