(i) You have formed the equation correctly; however, you have not explained how you derive at this equation. As of the solving, how did you find get 3-(-7)=x? The balancing concept behind the solving the solving of equation was not explained.(ii) The substitution is correctly done. You could have further elaborated that you are substituting the value obtained in (i) to find the length and breadth. So, why area = 23 cm x 10 cm? (could have pointed out the formula of area of rectangle).(iii) How did you get 1 m^2 = 1000 cm^2? What's the thinking behind the conversion after you mentioned that 1 m = 100 cm?The conversion is correctly done.cm^2 should be read as "square centimetre". This applies to m^2, too.