To be exact your term has to be written like this:
If you multiply a sum (written in brackets) you must multply each summand by the leading factor:
You have to observe the sign rules when multiplying: If the signs of the factors are equal (+*+ or -*-) the the result is positive (+) else it is negative.
Since 9 and 6 (of 6x) are positive numbers the result becomes:
You only can collect like terms, in this case you can collect the xes:
And now it's your turn to do the 2nd example.