By the binomial theorem,

I assume you meant to say "independent", not "indecent", meaning we're looking for the constant term in the expansion. This happens for k such that
12 - 3k = 0 ===> 3k = 12 ===> k = 4
which corresponds to the constant coefficient

Answer: x = 4 and y = -3
Step-by-step explanation:
2x + 4y = -4
2x = -4 - 4y
x = -2 - 2y
Now that we have solved the first equation for x, we plug (-2 - 2y) into the other equation in place of x and then solve for y.
3(-2 -2y) + 5y = -3
-6 - 6y + 5y = -3
-y = 3
y = -3
Now that we know y, we plug it into the original equation and solve for x.
2x + 4(-3) = -4
2x + -12 = -4
2x = 8
x = 4
You can check the answer by plugging both x and y into either of the original equations.
Here is how I would show the work for this problem
5- (a-4) = 3 (a+2)
5-a+4 = 3*a+3*2
5-a+4 = 3a+6
-a+9 = 3a+6
-a+9+a = 3a+6+a
9 = 4a+6
9-6 = 4a+6-6
3 = 4a
4a = 3
4a/4 = 3/4
a = 3/4
So the solution is the fraction a = 3/4 (in decimal form 0.75)
Let me know if you have any questions or issues with any of the steps shown above. It's a lot to take in so feel free to ask about anything really.