In a triangle, the total angle is 180 degrees. A straight line is always 180 degrees. With this in mind, the following can be obtained:

These are simultaneous equations.

A is the correct answer. When put into calculator, the decimals ends.
This is simply a question about ratios. This ratio means that for every 1 cm on the map, there are 12 km in actuality. You can set this problem up in fractions:
1 cm 12 cm
-------- = ----------
12 km x
To solve for x, we cross-multiply, for the moment ignoring units. Remember, your answer will be in km.
1*x=12*12
x=144
If x=144, then for 12 cm, there are 144 km.
Answer:
y=-0.215x^2+35
Step by Step:
Let,
,
,
, 
We know that, the general equation of the parabola.


Substitute the value of
in equation
and find the value of 







Hence, the equation of the parabola is:

You have t9 find a equal number