Answer:
18
Step-by-step explanation:
First, we have to find out the scale factor of the triangles. So, we go from 20 to 30 by:
[tex]20s=30\\s=3/2\\s=1.5[/tex]
1.5 is the scale factor. We're looking for x. We go from 12 to x by:
[tex]12*1.5=x\\18=x[/tex]
