Answer:
YB= 11.2
Step-by-step explanation:
These triangles use scale factors.
Using scale factors, we can see that 7/15 is as (7+YB)/(15+24). Those are equal fractions, so we can set them equal to each other and solve for YB.
(7/15)=((7+YB)/(39)) solving for YB we get that it is equivalent to 11.2.
