A sample of an ideal gas is taken through the cyclic process $\mathrm{ABCA}$ in the diagram. It rejects $50 \mathrm{J}$ of heat during the part $\mathrm{AB}$, does not absorb or reject the heat during $\mathrm{BC}$, and accepts $70 \mathrm{J}$ of heat during $\mathrm{CA}$. Forty joules of work is done on the gas during the part $\mathrm{BC}$, The internal energies at B and C, respectively, will be
[Given that Internal energy at A i.e ${\mathrm{U}}_{\mathrm{A}}= 1500$]