How do I find X thanks​

What is the value of x when x + 7 = 21?

Graph the system of inequalities presented here on your own paper, then use your graph to answer the following questions: y > 2x + 3y is less than negative 3 over 2 times x minus 4part a: describe the graph of the system, including shading and the types of lines graphed. provide a description of the solution area. (6 points)part b: is the point (â’4, 6) included in the solution area for the system? justify your answer mathematically. (4 points)

20.ju inces. which ordered pair is a viable solution if x represents the number of books he orders and y represents the total weight of the books, in ounces? (-3,-18) (-0.5, -3) (0,0) (0.5, 3)