Antimatter is not equal to matter any more than matter is equal to antimatter. The reason for this is that the properties of antimatter particles are defined as being opposite (specifically, as the antimatter version of that particle's properties) to those of the matter particle and its antimatter partner. For example, antimatter particles can have a negative mass, whilst normal matter particles can have a positive mass, and so the momentum of an antimatter particle is opposite to that of a matter particle, and both are equally valid definitions of momentum.
This leads to the concept that antimatter and matter are different aspects of the same thing. The first generation of matter particles, the up and down quarks, the electron and the electron neutrino, are created in equal numbers, and no antimatter particles are created. However, the second generation particles can be either matter or antimatter. The up and charm quarks can annihilate to produce the electron and a W Boson, which then decays into a muon and an antineutrino; the electron neutrino can either pair up with the electron to form the positron, in which case eight of them are annihilated, or it can get annihilated, leaving two fewer electrons in the universe.
Thus, whereas the first generation of matter particles and antimatter particles are created in equal numbers, the second generation is produced in either equal numbers of matter and antimatter, or in a ratio of 1:1, depending on the details of how the particles annihilate. The number of particles of the second generation is thus a measurement of the total amount of matter and antimatter in the universe.
This property of matter and antimatter to be ultimately the same thing, yet at different points along their lifetime, leads to a definition of total matter that is conserved, such that it is not affected by the annihilation of one type with its anticharacteristic. However, this is _conserved only for the sum of matter+antimatter_; since e.g. the rate of growth or decay is different for the two, there are no guarantees as to the net total. d2c66b5586