x mod m

HI,

I post on behalf of my friend

x mod m = a

x mod n = b



Let's say i choose small number...
m=5
n=*
a=*
b=*
then it's


x mod 5 = *

x mod * = *



after trying a but you will now that x=**
but how can i solve it easier than trying all kinds of
number.
I already got a formula like m*A+a = n*B+b but i have
two unknown A and B then, which is bad.
Any ideas?

regards Data