Fern's estimate is not correct because he rounded 548 wrong, it would be rounded to 550 instead since the number 8 is closer to 10. So the correct answer would be 420.
[] Similar
-> The triangles are similar because they were "mirrored" by the...
[] SSS
-> ... by the SSS similarity theorem, the sides are...
[] Proportional
-> ... the sides are proportional.
[] AB/AC
-> Since the sides are proportional, dividing corresponding sides will leave us with the same number
[] For the last two I think I am missing some information as I do not have any numbers and know where they got 85 from.
Have a nice day!
I hope this is what you are looking for, but if not - comment! I will edit and update my answer accordingly. (ノ^∇^)
- Heather
A fraction x/y is a ratio between two numbers x and y.
The ratio is preserved if both x and y are scaled up or down by the same number n.
This means you can obtain any fraction equivalent to x/y by multiplying both x and y by n, i.e. (n*x)/(n*y).
Then we have 1/4 = (2*1)/(2*4) = 2/8, for example.