Answer :
Just plug and chug to see which ones fit
120 = 50 + 35(2) → 120 = 50 + 70 → 120 = 120 yes this one works
335 = 50 + 35(6) → 335 = 50 + 210 → 335 = 260 no this doesn't work, and you don't need to go further because the question asks which ordered pair isn't a solution, which is (6, 335)