Hello! And thank you for your question!
For this equation we are going to first collect like terms by grouping:
(8 + 6.2) + (4a - 9a)
Then just simplify!
14.2 - 5a
But just realize. You can not subtract 14.2 - 5a. Because they are not the same term.
Final Answer:
14.2 - 5a