Answer:

Step-by-step explanation:
The given matrix addition is

We need to find the elements of matrix B.
Let 
Substitute the value of matrix.

After addition of two matrix we get

On equating both sides.






Therefore, the elements of matrix B are
.
Answer:The equation wth x in the information can be written as
1/2 x = 38.5 , Upon solving, the number = 77
Step-by-step explanation:
Let the number Sara was thinking about be x
halving the number to get an answer = 38.5 can be expressed as
1/2 X = 38.5
The equation with x in the information can be written as
1/2 x = 38.5
solving it becomes
1/2 x= 38.5
x = 38.5 x 2
x=77
The number Sara was thinking about = 77
Answer:
125.141
Step-by-step explanation:
Assuming that this is an equilateral triangle, I am going to divide this triangle in half to get a right triangle.
17 is our hypotenuse
17/2 = 8.5, this is one of our legs
The other leg is our height, which we will find.
We use Pythagoras Theorem to find the height/leg: 

= 14.72243186
Now, we use another formula to find the area of the triangle: 
14.72243186 × 17 = 250.2813416
250.2813416 ÷ 2 = <u>125.1406708</u>