Hi, may I please have a step-by-step explanation on how to figure out the answers for my Geometry study guide? Thank you so much!

20. 19. (2x - 40) ( x + 10)0 21. Solve for x and find the missing angle measures. 22. Which lines are parallel? Justify your answer. 23. Find the slope of the line containing the points D(10,-6) and F(-3,8). Write the equation of the line in slope-intercept form. 24. Which triangles are congruent? By what theorem? 25. Line x _ y and and line z Ly. What has to be true about lines x and z? 26. Find the measure of 21 and Z2 38 /70 21 27. Find the measure of each missing angle 70 860 28. Find the area of the shaded region A 3 cm 4 cm 12 cm 18 cm