12. Реши уравнение.

Решение:

Чтобы решить уравнения, нужно найти неизвестную переменную.

Раздел А:

1. \( x + 70 = 100 \)



\( x = 100 - 70 \)




\( x = 30 \)




2. \( x - 10 = 10 \)



\( x = 10 + 10 \)




\( x = 20 \)




3. \( 30 + c = 70 \)



\( c = 70 - 30 \)




\( c = 40 \)




4. \( 40 - x = 30 \)



\( x = 40 - 30 \)




\( x = 10 \)




5. \( y + 8 = 12 \)



\( y = 12 - 8 \)




\( y = 4 \)




6. \( y - 8 = 15 \)



\( y = 15 + 8 \)




\( y = 23 \)




7. \( 100 - c = 60 \)



\( c = 100 - 60 \)




\( c = 40 \)




8. \( b - 6 = 19 \)



\( b = 19 + 6 \)




\( b = 25 \)




9. \( a + 15 = 100 \)



\( a = 100 - 15 \)




\( a = 85 \)




10. \( c + 10 = 90 \)



\( c = 90 - 10 \)




\( c = 80 \)




11. \( b - 9 = 9 \)



\( b = 9 + 9 \)




\( b = 18 \)




12. \( 6 + a = 14 \)



\( a = 14 - 6 \)




\( a = 8 \)




13. \( c - 7 = 13 \)



\( c = 13 + 7 \)




\( c = 20 \)




14. \( 120 - y = 20 \)



\( y = 120 - 20 \)




\( y = 100 \)




15. \( b + 25 = 100 \)



\( b = 100 - 25 \)




\( b = 75 \)




16. \( 16 - a = 4 \)



\( a = 16 - 4 \)




\( a = 12 \)




17. \( c - 3 = 13 \)



\( c = 13 + 3 \)




\( c = 16 \)




18. \( 15 + x = 30 \)



\( x = 30 - 15 \)




\( x = 15 \)




19. \( 60 - c = 50 \)



\( c = 60 - 50 \)




\( c = 10 \)




20. \( 17 - a = 9 \)



\( a = 17 - 9 \)




\( a = 8 \)




21. \( 57 + b = 90 \)



\( b = 90 - 57 \)




\( b = 33 \)




22. \( a - 5 = 54 \)



\( a = 54 + 5 \)




\( a = 59 \)




23. \( 40 + y = 80 \)



\( y = 80 - 40 \)




\( y = 40 \)




24. \( c - 20 = 60 \)



\( c = 60 + 20 \)




\( c = 80 \)

Раздел Б:

1. \( 55 + y = 60 \)



\( y = 60 - 55 \)




\( y = 5 \)




2. \( 15 - x = 8 \)



\( x = 15 - 8 \)




\( x = 7 \)




3. \( y + 179 = 179 \)



\( y = 179 - 179 \)




\( y = 0 \)




4. \( 26 - b = 17 \)



\( b = 26 - 17 \)




\( b = 9 \)




5. \( a - 30 = 30 \)



\( a = 30 + 30 \)




\( a = 60 \)




6. \( 9 + x = 16 \)



\( x = 16 - 9 \)




\( x = 7 \)




7. \( c - 8 = 18 \)



\( c = 18 + 8 \)




\( c = 26 \)




8. \( 89 - y = 89 \)



\( y = 89 - 89 \)




\( y = 0 \)




9. \( c + 30 = 70 \)



\( c = 70 - 30 \)




\( c = 40 \)




10. \( y - 6 = 12 \)



\( y = 12 + 6 \)




\( y = 18 \)




11. \( 140 - y = 50 \)



\( y = 140 - 50 \)




\( y = 90 \)




12. \( 10 + a = 30 \)



\( a = 30 - 10 \)




\( a = 20 \)




13. \( 40 - b = 40 \)



\( b = 40 - 40 \)




\( b = 0 \)




14. \( x + 75 = 100 \)



\( x = 100 - 75 \)




\( x = 25 \)




15. \( x - 12 = 22 \)



\( x = 22 + 12 \)




\( x = 34 \)




16. \( 63 - c = 0 \)



\( c = 63 - 0 \)




\( c = 63 \)




17. \( b + 7 = 23 \)



\( b = 23 - 7 \)




\( b = 16 \)




18. \( 100 - y = 90 \)



\( y = 100 - 90 \)




\( y = 10 \)




19. \( 97 + c = 98 \)



\( c = 98 - 97 \)




\( c = 1 \)




20. \( 18 + b = 30 \)



\( b = 30 - 18 \)




\( b = 12 \)




21. \( a + 40 = 100 \)



\( a = 100 - 40 \)




\( a = 60 \)




22. \( b - 75 = 25 \)



\( b = 25 + 75 \)




\( b = 100 \)




23. \( 17 - a = 9 \)



\( a = 17 - 9 \)




\( a = 8 \)




24. \( c - 50 = 50 \)



\( c = 50 + 50 \)




\( c = 100 \)

Ответ: Решены все уравнения.