1: In the exam again, there are m students who get 90 points and n students who get 80 points. What is the average score of the two groups_______ Points? 2: When a is equal to 1, the value of fraction 3A minus 4 / a plus 2 is_________ ? 3: When the value of minus 3 of fraction x + 5 is a positive number, the value range of X is_____________ ? 4: If the fraction 2x minus X by 4 is meaningless, then x is equal to X________ ?

1: In the exam again, there are m students who get 90 points and n students who get 80 points. What is the average score of the two groups_______ Points? 2: When a is equal to 1, the value of fraction 3A minus 4 / a plus 2 is_________ ? 3: When the value of minus 3 of fraction x + 5 is a positive number, the value range of X is_____________ ? 4: If the fraction 2x minus X by 4 is meaningless, then x is equal to X________ ?

1.(90m+80n)/(m+n)
2.(a+2)/(3a-4)=-3
3.-3/(x+5)>0 x