Can someone help me with dimension change? | Geometry

1-for what value of x is line a parallel to line b 2-for what value of x is line a parallel to line b

Steve wants to develop a way to find the total cost of any item including sales tax. the sales tax in his city is 6%. his friend jenna writes the expression x + 6x where x is the cost of the item. explain whether her expression is correct based on the situation.

F(x)=x/2-2 and g(x)=2x^2+x-3 find (f+g)(x)