خواندن گزاره رایش (ریاضی) به زبان انگلیسی

ten percent

As far as my understanding goes, "10%" is not a proposition. It is a numerical expression which can be  (and often is) used as a noun phrase. The  "percent" part is  not pluralized.  

reading Reich's statement

ten percent  =  ده درصد

ten percent

ده درصد

a plus b

the sum of a and b