You need to use PEMDAS or the Order of Operation. P is parentheses, E is exponents, M is multiplication, D is division, A is addition, and S is subtraction. 8+5 is 13. There are No exponents or multiplication. Divide 13 by 1 and you get 13. So far, you have 1 + 13 - 3 - 13 + 4. If you do the addition you get 18 - 3 -13. 18 - 3 is 15. 15 - 13 is 2. Your answer is 2.