12. \\frac{(6 - 7)(5 - 3) - 18}{2(7 + 9) - -3(-4)}

Explanation:

Step1: Simplify numerator and denominator separately

Numerator:

First, simplify (6 - (-7)=6 + 7 = 13) and (5-(-3)=5 + 3=8). Then ((6 - (-7))(5-(-3))-(-18)=13\times8 + 18). Calculate (13\times8=104), so (104 + 18=122).

Denominator:

First, simplify (7 + 9 = 16), then (2(7 + 9)=2\times16 = 32). Next, simplify (-3\times(-4)=12), and (-[-3\times(-4)]=-12). So (2(7 + 9)-[-3\times(-4)]=32-12 = 20).

Step2: Calculate the fraction

The fraction is (\frac{122}{20}), which simplifies to (\frac{61}{10}=6.1).

Answer:

(6.1)