MathsGod1

I understand your method and you'd have to think when to add numbers randomnly.

I don't know how i got mines wrong it's not the same as your method but i got 4 in the end and the method got me there...?

14.5% of 215=31.175

$${\sqrt{{\mathtt{7}}}} = {\mathtt{2.645\: \!751\: \!311\: \!064\: \!590\: \!6}}$$

Ok, I'll do that but how does it turn from a positive to a negative number?

(Answer then is also -4)

Huh I'm not sure whether you mean negative 7x as its placed there or the operation sign minus?

So when you do that. I've been staring at the code for a long time now but I GET IT :D. 

You add rrlll instead of rrl and after qquad (before the brackets) you add an ampersand. 

I've done it on the same post (first comment).

\begin{array}{rrlll}
33-2x&=&5-9x\qquad&(- 5)\\
28-2x&=&-9x\qquad&(+9x)\\
28+7x&=&0\qquad&(which\;means)\\
28&=&7x\qquad&(28\div7=4)\\
x&=&4\\
\end{array}

I've edited my post. :) 

Thanks Melody and Alan!

I know that Alan, but i just skipped it or is that part vital for the equation?