This solution comes from Andrei from School No. 205, Bucharest, Romania.

To solve this problem I followed the following steps:

- associating to the letters of the alphabet numbers between 0 and 25, I transformed the coded message into a set of pairs of numbers $(\alpha \text{'},\beta \text{'})$

- I solved the system of equations for $(\alpha ,\beta )$ in terms of $(\alpha \text{'},\beta \text{'})$.

- I used the same association as in the first step, and I transformed the set of numbers $(\alpha ,\beta )$ into letters, and I found the message.

The association is:

	a	b	c	d	e	f	g	h	i	j	k	l	m	n	o	p	q	r	s	t	u	v	w	x	y	z
	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25

For each pair of numbers $(\alpha \text{'},\beta \text{'})$ I have to solve the system to determine $(\alpha ,\beta )$

${\displaystyle \begin{array}{cc}\multicolumn{1}{c}{\alpha \text{'}}& =\alpha +3\beta \hspace{0.5em}\hspace{0.5em}mod26\mathrm{\hspace{1em}\hspace{1em}\hspace{1em}}(1)\\ \multicolumn{1}{c}{\beta \text{'}}& =5\beta \mathrm{\hspace{1em}\hspace{1em}\hspace{1em}}mod26\mathrm{\hspace{1em}\hspace{1em}\hspace{1em}}(2)\end{array}}$

I start from the last equation:

${\displaystyle \beta =\frac{1}{5}\beta \text{'}\hspace{0.5em}\hspace{0.5em}mod26}$

To determine 1/5 (mod 26), I first constructed the table of multiplication for 5 (mod 26) to see where I obtain 1. As 21 multiplied by 5 gives 1 (mod 26) it follows that 1/5 (mod 26) is 21. This means:

${\displaystyle \beta =21\beta \text{'}\hspace{0.5em}\hspace{0.5em}mod26\mathrm{\hspace{1em}\hspace{1em}\hspace{1em}}(3)}$

and for $\alpha$ I obtained successively

${\displaystyle \alpha =\alpha \text{'}-3\beta =\alpha \text{'}-3\times 21\beta \text{'}=\alpha \text{'}-11\beta \text{'}\hspace{0.5em}\hspace{0.5em}mod26}$

that is

${\displaystyle \alpha =\alpha \text{'}+15\beta \text{'}\hspace{0.5em}\hspace{0.5em}mod26\mathrm{\hspace{1em}\hspace{1em}\hspace{1em}}(4).}$

Now, the sequence of numbers $(\alpha \text{'},\beta \text{'})$ is transformed by equations (3) and (4) into the sequence $(\alpha ,\beta )$

C	$\alpha \text{'}$	$\beta \text{'}$	$\alpha$	$\beta$	P
dj	3	9	8	7	ih
lb	11	1	0	21	av
rn	17	13	4	13	en
qm	16	12	14	18	os
bu	1	20	15	4	pe
ao	0	14	2	8	ci
hd	7	3	0	11	al
eo	4	14	6	8	gi
kr	10	17	5	19	ft
ia	8	0	8	0	ia
cs	2	18	12	14	mo
ud	20	3	13	11	nl
rx	17	23	24	15	yp
cm	2	12	0	18	as
qo	16	14	18	8	si
bn	1	13	14	13	on
fr	5	17	0	19	at
ld	11	3	4	11	el
ek	4	10	24	2	yc
th	19	7	20	17	ur
ys	24	18	8	14	io
wm	22	12	20	18	us

The message could be read as the quotation from Enstein talking about himself as a mathematician: 'I have no special gift. I am only passionately curious'.