Answer:
First image 30.44
second image 33.62
Step-by-step explanation:
First image

second image

Let the score on her seventh test be "x".
SO,

∴ He must get 104% on his seventh test to get an average score of 90%
Answer:
Using identify (a+b)(a-b) =a²-b²
Ur answer is (9b-1)(9b+1) =81b²-1
The equation of a circle:

(h,k) - the coordinates of the center
r - the radius
The center is (4,0), the length of the radius is 2√3.