I have been trying very hard to solve this type of congruence equation: $ax = b \pmod n$ and finally managed to actually solve a few by using properties like $\text{if}\quad \begin{cases} ax=b \pmod n \\ cx=d \pmod n \end{cases} \quad\text{then}\quad acx = bd \pmod n$ but still there are some simple congruences which I am not able to solve like $25x=15\pmod{29}.$
I tried to make use of both above and transitive property of congruences but that is not working here.
Now, I wanted to ask if is there any other method to solve congruences. I am asking this because I have very little knowledge of congruences. I have Burton's book of number theory and that helped me much better than Zuckerman's text did. But, still there are some topics that I am not able to do yet.