Standard EMF of a cell

2022 Phase 2 1 question

1. Two half cell reactions are given below. $Co^{3+}+e^-\rightarrow Co^{2+}$, $E^\circ_{Co^{2+}/Co^{3+}}=-1.81$ V $2Al^{3+}+6e^-\rightarrow 2Al(s)$, $E^\circ_{Al/Al^{3+}}=+1.66$ V The standard EMF of a cell with feasible redox reaction will be: