Based on this, since the number of cm is greater than the number of km, we can figure out that each cm should not be multiplied to get the km, so we can eliminate the first two answers.
Next write an equation to represent finding the scale
x=scale
11.5=2.3x
Now solve for the scale
11.5/2.3=2.3x/2.3
5=x
Therefore the scale is 5 centimetres = 1 kilometre
There are two triangles that are 15cm in height and 10cm in width so you do 15 times 10 which is 150 then divided it by 2 because it a triangle to get 75 then because there is 2 you then multiply it by 2 again and you get 150