a)[a=0]6781-6781=0
b)[b=57 460]67459-9999=57 460
c)[184]133+207=340,524-340=184
d)[49]98-42=56,56+38=94,94-45=49
a)[a=0]6781-6781=0
b)[b=57 460]67459-9999=57 460
c)[184]133+207=340,524-340=184
d)[49]98-42=56,56+38=94,94-45=49