38. Реши примеры: 18+5= 6+9= 14-5= 2)81:3*2= (100-55):9= 900-(500-300)= 400+(700-200)= 800-(300+100)= 7*9+17= 54:2:9=

Решение:

1. \( 18 + 5 = 23 \)

2. \( 6 + 9 = 15 \)

3. \( 14 - 5 = 9 \)

4. \( 81 : 3 \cdot 2 = 27 \cdot 2 = 54 \)

5. \( (100 - 55) : 9 = 45 : 9 = 5 \)

6. \( 900 - (500 - 300) = 900 - 200 = 700 \)

7. \( 400 + (700 - 200) = 400 + 500 = 900 \)

8. \( 800 - (300 + 100) = 800 - 400 = 400 \)

9. \( 7 \cdot 9 + 17 = 63 + 17 = 80 \)

10. \( 54 : 2 : 9 = 27 : 9 = 3 \)

Ответ: 23, 15, 9, 54, 5, 700, 900, 400, 80, 3.