Implement the function 𝐟(𝒂,𝒃,𝒄,𝒅)=∑(𝟒,𝟓,𝟕,𝟗,𝟏𝟏,𝟏𝟐,𝟏𝟑,𝟏𝟓) using 8:1 mux and 4:1 mux

8:1 MUX with a, b, c as select lines
4:1 MUX with a, b as select lines