you have to show the graph
Consider the triangle (<em>in </em><em>which </em><em>angle</em><em>4</em><em> </em><em>is </em><em>present</em>)
by angle sum property,
20 + 40 + angle4 = 180
60 + angle4 = 180
angle4 = 180 - 60
angle4 = 120
Also,
angle2 = 120 (vertically opposite angles)
angle1 + angle2 = 180 (linear pair)
angle1 + 120 = 180
angle1 = 180 - 120
angle1 = 60
See Quadratic Formula and Determinant's/Delta's formula
Where is the data chart to answer the questions?