Tolong dong kak pakai caranya​

K1 = 2 x (P + L)

K1 = 2 x (21 + 18)

K1 = 2 x 39

K1 = 78

K2 = π x d

K2 = 22/7 x 21

K2 = 22 x 3

K2 = 66

78 + 66

= 144