I think each girl had 8.1 points may be wrong
Answer:
0.25
Step-by-step explanation:
The answer is: (z - 6)(z + 15)
z² + 9z - 90 = z*z + 15z - 6z - 6*15 =
= (z*z + 15z) - (6z + 6*15) =
= z(z + 15) - 6(z + 15) =
= (z - 6)(z + 15)
do parentheses first which gives you 42-4+111 then aubtract to get 38+111 which equals 149
To find the mean, you have to add all the numbers then divide it by how many numbers there are.
In this case, you'll need to add all those numbers and divide it by 4.

The mean is 1995.