Respuesta :
9+r=99
99 being the product, means it is the total of Raj's score and 9. Therefore you add 9 + Raj's score, and you get 99. Raj's score was a 90.
"Product" refers to the answer obtained after performing multiplication, so...
[tex]99 = r * 9[/tex]
Divide by 9 on both sides to isolate r.
The answer is r = 11.