pls ya no 35 pakai cara

persentase pensil = 100% - 40% - 15% - 25 %
= 20%

maka 25/20 = 20/x  menggunakan cara perbandingan)
25x = 400
x = 16 lusin (C)

% pensil = 100% - 25% - 15% - 40%
= 20%
20/25×20= 400/25
= 16 lusin
semoga membantu.