The pair of angles given are alternate angles (they form a 'Z' shape). Alternate angles are always equal to each other. From this, we can get the equation:
14x - 13 = 8x + 5
Collect like terms,
6x - 13 = 5
6x = 18
x = 3
Hope this helped!! Ask me if there's any part of the working you don't understand :)
