Question

8+ =35-20                               18- =29-20                            -8=36-30  9+ =57-40                               12-  =60-56                           -7=49-43     6+ =24-10                               11- =95-90                            -5=18-9              

Answer 1

Подставим вместо неизвестного числа х и решим уравнение.

8 + x = 35 - 20

8 + x = 15

x = 15 - 8

x = 7

8 + 7 = 35 - 20

9 + x = 57 - 40

9 + x = 17

x = 17 - 9

x = 8

9 + 8 = 57 - 40

6 + x = 24 - 10

6 + x = 14

x = 14 - 6

x = 8

6 + 8 = 24 - 10

x - 8 = 36 - 30

x - 8 = 6

x = 6 + 8

x = 14

14 - 8 = 36 - 30

x - 7 = 49 - 43

x - 7 = 6

x = 6 + 7

x = 13

13 - 7 = 49 - 43

x - 5 = 18 - 9

x - 5 = 9

x = 9 + 5

x = 14

14 - 5 = 18 - 9

18 - x = 29 - 20

18 - x = 9

x = 18 - 9

x = 9

18 - 9 = 29 - 20

12 - x = 60 - 56

12 - x = 4

x = 12 - 4

x = 8

12 - 8 = 60 - 56

11 - x = 95 - 90

11 - x = 5

x = 11 - 5

x = 6

11 - 6 = 95 - 90

Answer 2

Let's break down the given equations one by one:

1. 8+ = 35-20 This equation is not valid. The "+" sign on the left side of the equation should have a number preceding it.

2. 18- = 29-20 This equation is also not valid. The "-" sign on the left side of the equation should have a number preceding it.

3. -8 = 36-30 This equation is correct. The left side of the equation, "-8," is equal to the right side, "36-30," as both sides evaluate to -8.

4. 9+ = 57-40 Similar to the first equation, this equation is not valid. The "+" sign on the left side of the equation should have a number preceding it.

5. 12- = 60-56 This equation is correct. The left side of the equation, "12-," is equal to the right side, "60-56," as both sides evaluate to 12.

6. -7 = 49-43 This equation is correct. The left side of the equation, "-7," is equal to the right side, "49-43," as both sides evaluate to -7.

7. 6+ = 24-10 Similar to the first and fourth equations, this equation is not valid. The "+" sign on the left side of the equation should have a number preceding it.

8. 11- = 95-90 This equation is correct. The left side of the equation, "11-," is equal to the right side, "95-90," as both sides evaluate to 11.

9. -5 = 18-9 This equation is correct. The left side of the equation, "-5," is equal to the right side, "18-9," as both sides evaluate to -5.

Therefore, out of the given equations, equations 3, 5, 6, 8, and 9 are valid.