Please look at picture!

Step-by-step explanation:

Look at the green triangles.

The first is a right isosceles triangle (it has a 90° angle and two legs are the same length).The second is an acute isosceles triangle (all angles are less than 90, and two legs are the same length).The third is an obtuse scalene triangle (it has an angle greater than 90, and all the legs are different lengths).The fourth is an obtuse isosceles triangle (it has an angle greater than 90, and two legs are the same length).

Scale is the ratio of the sizes.  So a scale of 2 means the triangle is twice as big.  A scale of 3 means the triangle is three times as big.  And a scale of 4 means the triangle is four times bigger.

Now let's look at the orange triangles.

a, j, and d are right isosceles triangles, just like the first green triangle.  Triangles that have the same shape are called "similar".  Now compare the scale, or size.  a is twice as big as the green triangle.  j is 3 times as big.  and d is 4 times as big.

Repeat for the other green triangles.  Match the shapes, then sort by size.  Don't let the orientation confuse you; the rotation of the triangle isn't important.

The final answer should be:

    j

a←↑→d

    f

g←↑→h

   c

b←↑→k

    i

e←↑→l