Question

what should be added to 4a-b+9c to obtain a+3b -4c​

Answer 1

add a+b-3,b-a+3,a-b+3

⇒a+b−3+b−a+3+a−b+3

⇒a+b+3.

Hope this was helpful.

Answer 2

Answer:

3a-4b+13c

Step-by-step explanation:

Let x be added

4a-b+9c+x = a+3b-4c

x = 4a-b+9c-(a+3b-4c)

x = 4a-b+9c-a-3b+4c

x = 3a-4b+13c