Draw out a number line with the values 0, 5, 10, 15, 20, 25, 30, etc (basically multiples of 5)
Then plot a point at 25
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Or you can draw out a number line with the multiples of 10, so with the values 0, 10, 20, 30, ...
Then plot a point at the exact midway point between 20 and 30 to represent the value 25
The diagram provided is an isosceles triangle. An isosceles triangle has two sides having equal measure and two base angles also having equal measure.
From the marks on the triangle given, line ZX and line ZY are equal in length. This also means angle X and angle Y are equal in measure.
Therefore, we would have;

This means angle X and angle Y both equal 27 degrees each.
Note that the sum of angles in a triangle is 180. Therefore, in triangle ZXY,
About 7.5 miles if you divide 45/3 is 15 so divide 15/2 which is 7.5