Question

{-20+(-7+9)3-[-7+9-(-1+5)]-(-1)3}

Answer 1

Espero ter ajudado.

$\boxed{\left\{-20+\left(-7+9\right)\cdot \:3-\left[-7+9-\left(-1+5\right)\right]-\left(-1\right)\cdot \:3\right\}}\\\\-20+2\cdot \:3-\left[-7+9-\left(-1+5\right)\right]-\left(-1\right)\cdot \:3\\\\-20+2\cdot \:3-\left(-2\right)-\left(-1\right)\cdot \:3\\\\-20+6-\left(-2\right)-\left(-1\right)\cdot \:3\\\\-20+6-\left(-2\right)-\left(-3\right)=\boxed{-9}$