Simplify the following equations
(this is algebra, so , only answer if you know for sure, you)
3b+11c-4b-c
9a-1+8c-8a+c
12c+5a+7+(-13c)+4a
-15-6c+3b-6c+9-2b

Mostly collect like terms
use associative property which is
(a+b)+c=a+(b+c)
and remember that:
you just use a general rule
x+x=2x
x^2+x^2=2x^2
3xy4xy=7xy
3x+4x^2=3x+4x^2
you can only add like terms( like terms are terms that are same name like x or y are differnt, and like terms have same power exg x^2 and x^3 and x^1/2 and such

so first one

3b+11c-4c-c
since they are all c except for the first one term, just assign a number for each so it simplifies to c times(11-1)+b(3-4)=c(10-1b=10c-b or

you just use a general rule
x+x=2x
x^2+x^2=2x^2
3xy4xy=7xy
3x+4x^2=3x+4x^2

second one9a-1+8c-8a+c
group like terms
(9a-8a)+(8c+c)-1=(a)+(9c)-1=a+9c-1

12c+5a+7-13c+4a
group like terms(12c-13c)+(5a+4a)+7
add like terms
-c+9a+7
the solution is 9a-c+7

-15-6c+3b-6c+9-2b
group like terms
(-15+9)+(-6c-6c)+(3b-2b)
-6+(-12c)+b=b-6-12c

the answers are:

10c-b

a+9c-1

9a-c+7

b-12c-6