Your local municipality introduced two different type tariff systems namely The two$-$part structure and The lifeline structure as from the first of March $2024.$ A two$-$part tariff is where you pay a fixed R$500\mathrm{.}00$ per month plus R$1\mathrm{.}55$ cents per kWh and the lifeline is where you pay R$2\mathrm{.}20$ cents per kWh$.$ Your family would like to find out which of the two tariff structures is the most cost$-$effective option.