5a+3[2b-3(a-b+2c)-(b-c)] 计算

题目

5a+3[2b-3(a-b+2c)-(b-c)] 计算

答案

5a + 3[2b - 3(a - b + 2c) - (b - c)]
= 5a + 6b - 9(a - b + 2c) - 3(b - c)
= 5a + 6b - 9a + 9b - 18c - 3b + 3c
= -4a + 12b - 15c