设 a/2 = b/3 = c/4 = k
所以
a = 2k
b = 3k
c = 4k
a + b + c = 27
2k + 3k + 4k = 27
k = 3
a - 2b - 2c
= 2k - 6k - 8k
= -12k
= -12×3
= -36
设 a/2 = b/3 = c/4 = k
所以
a = 2k
b = 3k
c = 4k
a + b + c = 27
2k + 3k + 4k = 27
k = 3
a - 2b - 2c
= 2k - 6k - 8k
= -12k
= -12×3
= -36