6. \( (90 \div 6) \times\{-2+[3 \times(5+1)-(8-4)+3]\} \) 7. \( [7 \times 10-11] \times(5 \times 2)+[(15 \div 3) \times 8] \) 8. \( [(3 \div 3) \times 2-2+5 \div(4+1)]+(6 \times 4) \)

To solve the first expression \( (90 \div 6) \times\{-2+[3 \times(5+1)-(8-4)+3]\} \), first compute \( 90 \div 6 = 15 \). Next, simplify the inner expression: \( 5 + 1 = 6 \), so \( 3 \times 6 = 18 \). Then calculate \( 8 - 4 = 4 \), leading to \( -2 + 18 - 4 + 3 = 15 \). Now multiply, \( 15 \times 15 = 225 \). For the second expression \( [7 \times 10-11] \times(5 \times 2)+[(15 \div 3) \times 8] \), begin with the brackets: \( 7 \times 10 = 70 \) and \( 70 - 11 = 59 \). Then \( 5 \times 2 = 10 \) and, multiplying these gives \( 59 \times 10 = 590 \). For the other part, \( 15 \div 3 = 5 \) and then \( 5 \times 8 = 40 \). Finally, adding these results gives \( 590 + 40 = 630 \). Lastly, for \( [(3 \div 3) \times 2-2+5 \div(4+1)]+(6 \times 4) \), simplify the brackets: \( 3 \div 3 = 1 \), hence \( 1 \times 2 = 2 \). The full expression reads \( 2 - 2 + 5 \div 5 = 2 - 2 + 1 = 1 \). Now calculate \( 6 \times 4 = 24 \), leading to a final sum of \( 1 + 24 = 25 \). So the final answers for the expressions are: 6. \( 225 \) 7. \( 630 \) 8. \( 25 \)