Trigger bonus with combination of symbols

Hello everybody :)

Im very new in this field and i start step by step to understand and learn this math world of slots machine.

Me and my friends start to develop a slot game 5x3. After a long discussions with my friends , they want to trigger a bonus game, not with a single symbols but with a combi of 2. When the sym1 has the sym2 on his right with the distance of a symbol we trigger a bonus game.

From my understanding based on 5 reels we have 3 posible winnings:

REEL1 REEL2 REEL3 REEL4 REEL5
SYM1 X SYM2 X X
X SYM1 X SYM2 X
X X SYM1 X SYM2

How can i calculate the hits and probability in order to understand how often this bonus games is triggered?? Finaly i would like to Find The RTP.

Thank so much in advance and I hope i dont double this question, but after a long search i did not find anything.

If was just a symbol, was clear for me. But here im talking about a Event ..... combi of 2 symbols trigger some Bonus.

Can anyone help me ? :( please

I think it's as simple as mapping out every combination of reel stops over the five reels, and then counting up the combinations where your symbols would trigger?

S-o i need to make a combination payline :) and after to identify The winning combination?