1. Stating the problem: Calculate the value of the expression $$400 \div 50 + 320 \div (50 \cdot 90)$$ and $$810 \div (810 \div 9) + 45 \div 5$$. 2. Recall the order of operations: division and multiplication are performed from left to right. 3. Calculate the first expression step-by-step: - Calculate $$400 \div 50 = 8$$. - Calculate the denominator in the second term: $$50 \cdot 90 = 4500$$. - Calculate $$320 \div 4500 \approx 0.0711$$. - Add the two results: $$8 + 0.0711 = 8.0711$$. 4. Calculate the second expression step-by-step: - Calculate the inner division: $$810 \div 9 = 90$$. - Calculate $$810 \div 90 = 9$$. - Calculate $$45 \div 5 = 9$$. - Add the two results: $$9 + 9 = 18$$. 5. Final answers: - First expression: $$8.0711$$ (approximately) - Second expression: $$18$$