Fast which equation is not an identity?

a) 0+7=7

b) 1∙9=9

c) x+3=3+x

d) x+1=x

21. which equation has no solution?

a. 7y + 9 = −7y − 9

b. 5x + 2 = 5x − 3

c. 4v − 3 = 4v + 6 − v

d. 2z + 1 = 3z − z + 1

22. solve the following equation

3x + 4 = 5x − 10

23. solve the following equation
2(2x + 1) = 4x − 5

24. solve the following equation
−2x − 2 = 2(3x − 1) − 4(−6 + 5x)