Tolong, no 2 dan 3. Beserta caranya, ingat, jgn asal2an!

jawab

2) A = (0,1,2,3,...,9)
n(A) = 10

bilngan ats 4 angka dan  anghka selalu di awal
= 1 x 8 x 7 x 5
= 280


3).  
p= 10 
l=  8 

Luas arsir = (10 x 8) -  1/2 [(4x5) + (6x3) + (8x5) +(2x3)]
L = 80 - 1/2 (84)
L = 80 - 42
L = 38