Plz Help! What is the value of x?

Can someone me with this problem . show your work .

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)