6(4x + 5) = 3(x + 8) + 3
24x + 30 = 3x + 24 + 3
24x + 30 = 3x + 27
24x - 3x = 27 - 30
21x = - 3
x = -3/21
x = - 0.143 <==
If this exact question is repeatedly deleted, it's probably because of the ambiguity of the given equation. I see two likely interpretations, for instance:

or

If the first one is what you intended, then

and it follows that
2<em>k</em> + 8 = 3 ==> 2<em>k</em> = -5 ==> <em>k</em> = -5/2
If you meant the second one, then

which would give
<em>k</em> + 9 = 3 ==> <em>k</em> = -6
And for all I know, you might have meant some other alternative... When you can, you should include a picture of your problem.
Answer:
5683.2 Euro's
Step-by-step explanation:
i=
p=7400 Euro's
r=12.8*1/100
t=6yrs
I=P*R*T
7400*12.8/100*6
=5683.2 Euro's
You multiply radius by 3.14 by the height if you plug it in your equation is 8×3.14×15 which equals 1005.31 which rounds to 1005, the answer is 1005! :D