By comparing standard reduction potentials, we can compare the reduction and oxidation powers of elements or ionic species. Some standard reduction potential values are given in Table 1.
What is the overall cell potential for a cell which is formed with Ni/Ni2+ and Ag/Ag+ half-cells?
Now, it is just a matter of adding the individual potentials to get the overall potential. A word of caution: when you add the individual half-electrode potentials, make sure that the appropriate sign has been assigned to them.