Answer :
To answer this problem, let's call:
P: monthly budget
[tex]P_e:[/tex] Electricity expenditure
[tex]C_e:[/tex] Consumption of household appliances.
[tex]C_a:[/tex] Consumption of kitchen appliances.
We know that:
[tex]\frac{1}{12}P = P_e[/tex]
[tex]\frac{4}{5}P_e = C_e[/tex]
[tex]\frac{3}{4}C_e = C_a[/tex]
[tex]C_a = 80[/tex]
Then, if [tex]C_a = 80[/tex]:
[tex]\frac{3}{4}C_e = 80[/tex]
[tex]C_e = 80(\frac{4}{3})[/tex]
[tex]C_e = 106.67[/tex]
[tex]\frac{4}{5}P_e = 106.67[/tex]
[tex]P_e = 106.67(\frac{5}{4})[/tex]
[tex]P_e = 133.34[/tex]
Finally:
[tex]\frac{1}{12}P = 133.34[/tex]
[tex]P = 133.34(12)[/tex]
[tex]P = 1600.05[/tex] €
The entire budget was € 1,600