1. The problem is to evaluate the expression: $3 - 4 + 5 + 7$. 2. The formula used here is simple arithmetic addition and subtraction. 3. Perform the operations from left to right: $$3 - 4 = -1$$ 4. Then add 5: $$-1 + 5 = 4$$ 5. Finally, add 7: $$4 + 7 = 11$$ 6. Therefore, the final answer is $11$.