The two slopes are the key features. If the slopes are different, the two linear function will intercept.
You are to follow the clues. Since is is 2 digits and is prime, go through the prime numbers between 10 and 20. They are 11, 13, 17, and 19. Then you find the factors of 34 which are 1×34 2x17. That leaves only 1 possible answer: 17
