Answer:
A:102
Step-by-step explanation:
We are given that the points A(0,0),B(0,4a-5) and C(2a-+1,2a+6) form a triangle.
If angle ABC=
We have to find the area of triangle ABC
If angle ABC= 90 degree
From given below figure 




Substitute the values then we get 
B(0,17) and C (12,17)
Distance formula 

AB=
BC=
BC= units
 units
Area of triangle =
Substitute the values 
Then we get
 Area of triangle ABC=
Area of triangle ABC=102 square units
Answer: A: 102
 
        
             
        
        
        
Answer: h = 9
Step-by-step explanation: A system of linear equations is consistent when it has at least one solution. 
The matrix given is:
![\left[\begin{array}{ccc}-15&21&h\\5&-7&-3\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-15%2621%26h%5C%5C5%26-7%26-3%5Cend%7Barray%7D%5Cright%5D)
Transform this matrix in a row-echelon form:
![\left[\begin{array}{ccc}-15&21&h\\5&-7&-3\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-15%2621%26h%5C%5C5%26-7%26-3%5Cend%7Barray%7D%5Cright%5D) 
    
 ![\left[\begin{array}{ccc}-15&21&h\\0&0&-9+h\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7D-15%2621%26h%5C%5C0%260%26-9%2Bh%5Cend%7Barray%7D%5Cright%5D)
For this row-echelon form to have solutions:
-9 + h = 0
h = 9
For this system to be consistent: h = 9.
 
        
             
        
        
        
Answer: 12 acres could be planted (at most)
Step-by-step explanation: Since there will be twice as many acres of wheat in  comparison to the corn, out of the total 36 acres at least 24 of those will need to be wheat. That leaves 12 acres left for the corn.