Question

Is there any mistake

Answer 1

Yes

Explanation:

Number 3 the last table. For the output of y being 21 the input should not be 11. it should be 22

21=1/2x+10
multiply whole equation by 2

42 = x+20
subtract 20 from both sides

22=x

OR

21=1/2x+10
subtract 10

11=1/2x
divide by the 1/2 (aka multiply by 2)

x=22