how to transform word problem to an equation ?? is there any trick for this? A team f eleven spies were assigned consecutive whole numbers divisible by eleven as their identity code . For telephonic contact they have to use contact code that equals the product of the middle of the identity code and sum of all identity code of the eleven spies . if last of the identity is 209 then the contact code is ________ .

I am totally blank in this question . 

What i Have done is :

no. Spies =11,

S= 11s1+ 12s2+13s3+14s4+......21s11 ..

now i am Confusing what to do  ...
You were given that $s_{11} = 209$.  Since the identity codes consist of consecutive multiples of $11$, 

$$s_1 = s_{11} - 10 \cdot 11 = 209 - 110 = 99$$

giving the sequence of identity codes $\{99, 110, 121, 132, 143, 154, 165, 176, 187, 198, 209\}$.  Try to complete the problem from there.
Its a old question  i was just solved it for my exams and i came up with the solution. Its a bit tricky question

Spies = 11

{S1,S2,S3,S4,S5,S6,S7,S8,S9,S10,S11}

and their codes will be
{99,110,121,132,143,154,165,176,187,198,209}

Sum of Spies codes = 1694

Product of the middle of the codes = 1*2*3*4*5*6*7*8*9*0 = 0

So the contact code will be 0 + 1694 = 1694