Question

If 9a+6b+4c=7, what is -24b-16c-36a

Answer 1

Rearrange the 2nd equation

-36a-24b-16c

divide the whole thing by 4 and you'll get
-9a-6b-4c

you'll realize it looks the same as your first equation except that all the + has become minus so the answer will be -7 instead for your new equation
-9a-6b-4c=-7

multiply the whole thing by 4 and you'll get
-36a-24b-16c = -28

so the answer you want is -28