If f(a)=2a+6, what is the value of (f(2a)+f(a)) ? Choose the correct choice from the following:  A) 2a-4  B) 8a-7  C) 9a+5  D) 6a+12  E) 3a+5
f(a)=2a+6   f(2a)= 4a+6   (f(2a)+f(a)) = 4a+6+2a+6 = 6a+12   Answer is 6a+12
<result>D</result>
If f(a)=2a+6, what is the value of (f(2a)+f(a)) ?