She distributed the 4 to the 2x-1, giving her 9+ 8x -4. she subtracted 8x from both sides leaving her with 4=9-4 which is the same as 4=5
The first thing we must do for this case is find the scale factor.
We have then that for the larger side of both triangle, the scale factor is:

To find the other two sides, we must apply the scale factor on each side of the triangle FGH.
We have then:
For PQ
For QR
Answer:
You have that the lengths for the other two sides of triangle PQR are:
The first ones b.........
Here we are:
Triangle PQR is equilateral, all the angles are 60, this means that triangle PSR is an isosceles triangle. 180-90=90 90/2=45 60-45=15
B=15
Hope this helps :)
You do (12/300)x100 and it is going to give you the a answer