math
posted by a student is selected at is the probability the th on .
a student is selected at is the probability the the randomly selected stundent is neither a 10th grade nor an 11th grade express your answer in fraction in simplest form

Please reread your post. Does it make sense to you? Clarify and repost if you want help.
Also  what grades are being considered in addition to 10th and 11th? 
i am good at math i go to school every day i love school so much i love my teacher and my school is name is sonoran sky

im not good on math but i like. math i don't now what can i do to be good on math.