I think #7 is 40
#9 is 300
The perimeter of a triangle is the sum of all side lengths of the triangle. The numerical expression for the perimeter of Stephanie's triangle is: 
Let the sides of Juan's triangle be x, y and z. So:

The perimeter (J) of Juan's triangle is calculated by adding all sides.
So:

This gives:


From the question, we understand that:
The perimeter (S) of Stephanie's triangle is half that of Juan.
This means that:

Substitute 25 for J

Hence, the numerical expression for the perimeter of Stephanie's triangle is: 
Read more about perimeters at:
brainly.com/question/11957651
Equation a^2 + b^2 = c^2
c = longest side, unknown
The answer is D.
12^2 + 10^2 = c^2
Answer:
Step-by-step explanation:
Hello!
The variable of interest is:
X: number of daily text messages a high school girl sends.
This variable has a population standard deviation of 20 text messages.
A sample of 50 high school girls is taken.
The is no information about the variable distribution, but since the sample is large enough, n ≥ 30, you can apply the Central Limit Theorem and approximate the distribution of the sample mean to normal:
X[bar]≈N(μ;δ²/n)
This way you can use an approximation of the standard normal to calculate the asked probabilities of the sample mean of daily text messages of high school girls:
Z=(X[bar]-μ)/(δ/√n)≈ N(0;1)
a.
P(X[bar]<95) = P(Z<(95-100)/(20/√50))= P(Z<-1.77)= 0.03836
b.
P(95≤X[bar]≤105)= P(X[bar]≤105)-P(X[bar]≤95)
P(Z≤(105-100)/(20/√50))-P(Z≤(95-100)/(20/√50))= P(Z≤1.77)-P(Z≤-1.77)= 0.96164-0.03836= 0.92328
I hope you have a SUPER day!
Answer:
9x squared + 12x
Step-by-step explanation: