let us represent the question with a diagram for better understanding.
Using Pythagoras theorem
![\begin{gathered} c^2=12^2+9^2 \\ c^2=144+81 \\ c=\sqrt[\square]{225} \\ c=15\text{ km} \end{gathered}](https://tex.z-dn.net/?f=%5Cbegin%7Bgathered%7D%20c%5E2%3D12%5E2%2B9%5E2%20%5C%5C%20c%5E2%3D144%2B81%20%5C%5C%20c%3D%5Csqrt%5B%5Csquare%5D%7B225%7D%20%5C%5C%20c%3D15%5Ctext%7B%20km%7D%20%5Cend%7Bgathered%7D)
The distance between the parents and grandparent house = 15 km
It's the last option.
The area of a triangle can be calculated by multiplying the base and the height, and multiplying the product by 1/2.
Answer:
1. {5,-9}
2.{4}
3.{9/2}
Step-by-step explanation:
The equation
can be solved as follows:




Then, the solutions of the equation are
.
Now, if
, we can solve the equation
as follows:




So, the unique solution of this last equation is 
The last equation is
, where
. To solve this equation we can proceed as follows:







But, x=11/4 is not a solution of this equation. So the unique solution is x=9/2.
According to the given information, taking x as the number:

Solve the equation to find the number:

The number is 60.