Already average of two subjects is (70+80)/2 = 75%
To maintain the percentage at 75%, he shouls get 75% marks in third subject
a student got 70% in one subject,80% in other.to get overall 75% how much he should get in third subject.
Options:
  * 65%
  * 75%
  * 85%
  * 95%
  * 88%