MathsWatch marking answers as wrong when they are clearly correct

F12(Inspect element) and fiddle with the console, ie check if there is any errors. I can't really help you here because I don't use it .

Automated systems such as that tend to be much more sensitive to nomenclature differences and potential typos than hand marked work. Even just including or omitting a space somewhere can lead to it marking something as incorrect. This doesn't actually have any bearing on your ability to do maths, so I wouldn't worry too much about it. If there is a question you are getting marked incorrect but you're certain is correct, you can always ask on here, showing your working, if it is correct. This will ensure you are able to do the work you need to without worrying about computer errors.

99% is very good

I will post the rest of the working

I will post the rest of the working

That all looks fine. You haven't shown that $b^2=49 \Rightarrow b = \pm 7$ (and then discount the negative solution) but that won't be necessary on Mathswatch.

Also, please post maths questions in the maths forum in future

Wow, your homework is out of 538? Your teachers must love you

Thank you! It worked

Just in case you're not aware, your working was perfectly fine and Mathswatch should have accepted it. I'm glad you managed to sort it.

let the consecitive odd no.s be 2n+1 and 2n+3
(2n+1)^2= 4n^2+4n+1
(2n+3)^2= 4n^2+12n+9
(2n+3)^2 - (2n+1)^2
=8n + 8
Factorises to 8(n+1)
any number multiplied by 8 is a multiple of 8