Answer:
(a) = 0.32 or 8/25
(b) = 0.48 or 12/25
(c) = 4 Boards
Step-by-step explanation:
(a):
0.8 x 2/5
8/10 x 4/10
(8 x 4) / (10 x 10)
(32) / (100)
0.32 or 8/25
(b):
0.8 x 3/5
8/10 x 6/10
(8 x 6) / (10 x 10)
(48) / (100)
0.48 or 12/25
(c):
0.8 x 5
8/10 x 50/10
(8 x 50) / (10 x 10)
(400) / (100)
4 Boards