What value can i put for x on 4(x+3) = 4x+3

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.

It says factor each expression 49x-28?

Factor the expression using the gcf. the expression 21m−49n factored using the gcf