a.     Need

A B C D

P0  0 0 0 0

P1  0  7  5  0

P2  1  0  0  2

P3  0  0  2  0

P4  0  6  4  2

 

b.Since(0,0,2,2)<=(1,5,2,0),the system is safe.

c.   Need        Available

ABCD        ABCD

P0 0000          1 100

P1 0330

P2 1002

P3 0020

P4 0642

The system is safe,so the request can be granted immediately.