I've been reading up on the uses of the linear expenditure system via a the papers which apply them. 

One paper which gives a good introduction to the topic in a paper called:
<a href="https://repub.eur.nl/pub/18250/">Modeling household behavior in a CGE model:
linear expenditure system or indirect addilog? by Paul de Boer</a>. (pages 5-6) It goes through the basic theory behind the linear expenditure system fairly well. 

However in terms of working out the mathematics myself i'm having some difficulty, below is an abridged version of what is found in the paper.

>To derive the linear expenditure system we have:
$$\max \ \ \ \ \ \ U(x_1,...,x_n)=\sum_{i=1}^n\gamma_i ln(x_i-a_i)$$
$$s.t.\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ m=\sum_{i=1}^n p_ix_i$$

>where $\sum_{i=1}^np_ia_i$ is our _subsistence expenditure_. 

>After computing this we should get our linear expenditure system which is defined as:

>$$p_ix_i=p_ia_i+ \gamma_i(m-\sum_{j}p_{j}a_j)$$

where $(m-\sum_{j}p_{j}x_j)$ _supernumerary or discretionary expenditure_.

This is not what I got.

when solving this I end up with this (like how it was previously derived on https://economics.stackexchange.com/questions/8633/linear-expenditure-system-of-demands-derivation-help):

$$\sum_{i=1}^nx_i=(a_1,...,a_n)+\left(\frac{\gamma_1}{\lambda p_1},...,\frac{\gamma_1}{\lambda p_1}\right)$$

How do i get the result like that in this paper?