Inflow - Outflow = Change in storage (which is in turn change in elevation × area)
Net Inflow into the lake = Inflow by 3 rivers + Precipitation $$ = (52\ \mathrm{m^{3}/s} \times 122 \times (30\ \mathrm{days}+31+30+31)\times24\times60\times60 + 0.1\ \mathrm{m}\times100\times10^3 \mathrm{m}^2) $$
Total Outflow = Outflow + Evaporation $$ = (45\times122\times24\times60\times60 + E), $$ where E is the component to be found.
Change in storage = Change in elevation × Area $$ = (571.10 - 571.04)\times100 \times 10^6 E = 0.68\ \mathrm{m} $$