"The maths of grade nine is much more difficult than that of grade ten."
"Grade nine maths is much more difficult than grade ten maths."
Perhaps that's what you mean. If it is, I'd suggest that it possibly only seems more difficult because, in grade nine, the initial concepts that grade ten maths relies on are taught.
Post #1 "Ninth class mathematics is much more difficult than of tenth class". Post #4 Correction for post 1. "Nineth class mathematics is much more difficult than of tenth class".
Do you even read the responses that people here take the time to give you, tufguy?
But I was told I misspelt "ninth" and I had written the same spelling thats why I did the correction and I had to use the same words that I used in original question. I just had to correct the spelling but you are saying "ninth" is correct, "nineth" is incorret.
I corrected it in the original title as I didn't want to keep reading nineth in perpetuity on the opening page or to have other students thinking it was correct.