When you're combining 'like terms', look for all the terms that end with 'ab'.
Then add all the numbers that have 'ab' after them.
You can use desmo its a site that helps graph
The question is asking to convert the said decimal value in a simplest fraction form, base on my research and further calculation, I would say that the answer would be 3/10. I hope you are satisfied with my answer and feel free to ask for more