Answer:
7+2(a-3)=-9
a= -5
Explanation:
7+2(a-3)=-9
Distribute  2 through the parentheses 
Example: 7+2a-6=-9
Next: 7+2a-6=-9 
Subtract the numbers 
1+2a=-9
Move constant to the right hand side and change its sighn 2a=-9-1
2a=-9-1
Calculate the difference 
2a=-10
Divide both sides of the equation by 2
Answer: a=- -5