Answer:
x = 7
Explanation:
Since the triangles are similar the ratio of the sides must be the same
AB AK
------- = --------------
QN NP
9 12
---------- = ------------
2x+1 3x-1
Using cross products
9(3x-1) = 12(2x+1)
Distribute
27x -9 = 24x +12
Subtract 24x from each side
3x-9 = 12
Add 9 to each side
3x = 21
Divide by 3
x = 7