Answer:
x = 31°
Explanation:
To find x we must first find the other unknown angle within the left-hand triangle. We will call this angle ∡.
The bottom side of the triangle (between 72° and y) is a straight line. Therefore, if there is a line cutting this one, (dividing the left and right triangles in this case) then the two angles either side of this center line will add to equal 180°. Since we have been given one of these angles in the example (103°) We can subtract this from 180° to find this angle. Hence:
∡ = 180 - 103
∡ = 77
Now we have two of the three internal angles within this triangle, we can use the knowledge that all internal angles will add to 180° to find x. Hence:
x = 180 - 72 - 77
x = 31°