The total number quarks in a helium nucleus which is composed of 2 protons (positively charged particle) and 2 neutrons (uncharged particle) is:
Since there 3 quarks in each nucleon, 4 nucleons would have a total of 12 quarks. to work this out, just simply multiply 3 quarks to the number of nucleons:
So,
3 (quarks) x 4 (nucleons) = 12 quarks
Therefore, there are 12 quarks in 4 nucleons.