Can sum 1 wit dis qustion plz?

Hello!

You first have to find the scale factor between the triangles

To do this you divide the new side length by the old one

9 / 6 = 1.5

They multiplied the smaller triangle by 1.5 to get the bigger one

Do this to find the missing length

8 * 1.5 = 12

The answer is 12

Hope this helps!