Salut.
25 - {27 ÷ [(a - 27 ÷ 3) ÷ 3] + 42 ÷ 7 × 3} = 4
27 ÷ [(a - 27 ÷ 3) ÷ 3] + 42 ÷ 7 × 3 = 25 - 4
27 ÷ [(a - 27 ÷ 3) ÷ 3] + 42 ÷ 7 × 3 = 21
27 ÷ [(a - 9) ÷ 3] + 6 × 3 = 21
27 ÷ [(a - 9) ÷ 3] + 18 = 21
27 ÷ [(a - 9) ÷ 3] = 21 - 18
27 ÷ [(a - 9) ÷ 3] = 3
(a - 9) ÷ 3 = 27 ÷ 3
(a - 9) ÷ 3 = 9
a - 9 = 9 × 3
a - 9 = 27
a = 27 + 9
[tex]\boxed{a=36}[/tex]
- Lumberjack25
