You have 3 isotopes of an element. The mass number for each isotope
is represented by the letters A, D, and E.
The isotope with a mass of A is 33% abundant. The isotope with a mass
of D is 67% abundant. The isotope with a a mass of E is 33% abundant.
Which expression represents a way to calculate the atomic mass of this
element?
1A(0.33)+D(0.67)+E(0.33)
2A(33)+D(67)+E(33)
3 [A(33)+D(67)+E(33)1/3
4.A(0.33)+D(0.67)+E(0.33))/3

Help me which one is it