Question

what should be added to a+b+c to get 2a-b-3c​

Answer 1

Step-by-step explanation:

Let the number be x.

(a+b+c) + x = (2a-b-3c)

x = (2a-b-3c) - (a+b+c)

x = 2a-b-3c-a-b-c

x = a - 2b - 4c

a- 2b-4c should be added to a+b+c to get 2a-b-3c.