( 100y+x)-350 = 2 *( 100 x+y)，
Where x and y are integers, and 0 ≤ x, y.
Simplified equation
98y= 199x+350，
(picture)
3x+56 must be an integer multiple of 98, that is:? 3x+56=98k
When k= 1, then x= 14, at this time.
When k=2, x has no integer solution.
X> 100 when k=3.
That is, the face value of Li Lin's cheque is 14.32 yuan, which was mistaken for 32. 14 yuan when it was exchanged.
Request: Li Lin should return 32.14-14.32 =17.82 yuan.