[45+45=] its would be something like cuarenta y cinco y curaenta y son noventa
[45+45=] its would be something like cuarenta y cinco y curaenta y cinco son noventa
u missed a "cinco", but its fine
(why do they teach stuff like that? a "normal" spansih would say "cuarenta y cinco más cuarenta y cinco igual noventa
"
Aaaanyway, u are *almost* right