-81 x 128 ---------------- -81 × (-512) help please? ?

[tex]\frac{-81\times128}{-81\times(-512)}=-\frac{128}{512}=-\frac{128}{128\times4}=-\frac{1}{4}[/tex]

(-81 × 128) ÷ (-81 × (-512)) = ((-9 × 9) × (4 × 32)) ÷ ((-9 × 9) × (-16 × 32)) = 4 ÷ (-16) = -0,25