(x - 4)(x - 3), First find the factors of x^2 which is x and x so write that down of the left sides of both brackets. Next, find the factors of 12 that when added gives you the middle number which is -7 and i got 3 and 4 so write that down in the right sides in the brackets. Lastly you need to know the signs so now since its + 12 you need the signs that give you a positive number which is - and - but its also + and +, so look at the middle number its -7x so +3 +4 wont give you -7x but -3 - 4 will so that your answer,
Hope this helped!