1/
`A = (-3 +6) . (-4) - 12`
`A = 3 . (-4) - 12`
`A = -12 - 12`
`A = -24.`
`B = 3/5 + `$\dfrac{-7}{10}$`.(-2) `
`B = 3/5 + 7/5`
`B = 10/5`
`B = 2.`
2/
`2x = 3/4 - 5/6`
`2x = 18/24 - 20/24`
`2x = ` $\dfrac{-1}{12}$
`x = `$\dfrac{-1}{12}$` : 2`
`x = `$\dfrac{-1}{12}$` . 1/2`
`x = `$\dfrac{-1}{24}$.