It takes 7 minutes and 30 seconds to travel 5 kilometers because first you divide 3 and 2 to figure out how many minutes is 1 kilometer and you get 1.5 then you multiply 5 and 1.5 to get the minutes of 5 kilometers. Also the kangaroo travels 1.3 kilometers in 2 minutes
The sum of the inner angles of any triangle is always 180°, i.e. you have

In the particular case of an equilater triangle, all three angles are the same, so

and the expression becomes

which implies 
So, if you rotate the triangle with respect to its center by 60 degrees, the triangle will map into itself. In particular, if you want point A to be mapped into point B, you have to perform a counter clockwise rotation of 60 degrees with respect to the center of the triangle.
Of course, this is equivalent to a clockwise rotation of 120 degrees.
Finally, both solutions admit periodicity: a rotation of 60+k360 degrees has the same effect of a rotation of 60 degrees, and the same goes for the 120 one (actually, this is obvisly true for any rotation!)
Answer:
250 boys
Step-by-step explanation:
We know that the ratio is 9:10 from girls to boys
Take 225 and divide it by 9
225 ÷ 9 = 25
So we know that 25 is a factor of 225
We can the number of boys and multiply it by 25 to get 250
If we put it in the ratio form:
225:250 = 9/10
Check work:
25 x 9 = 225
25 x 10 = 250