What is the solution to the equation?

3x + (4/5) = 7 - 2x

Henry places x marbles into an empty bucket.  Each marble has the same weight.  
The weight, in ounces, of the bucket and marbles can be calculated using the expression shown.

​3x + 8

What does the term 8 represent in this expression?
A.)  the weight of each marble
B.)  the weight of the empty bucket
C.)  the number of marbles in the bucket
D.)  the total weight of the bucket and marbles

The graphs of two functions, f(x) and g(x), where g(x) = f(x) + h, are shown.

Based on the graph, what is the value of h?