Answer:
10
Step-by-step explanation:
ABC is similar to RST,
so BC is corresponding to ST, and AC is corresponding to RT
BC=12 and ST=8
so the scale factor from RST to ABC is 1.5 and the scale factor from ABC to RST is 2/3 because 12*(2/3) is 8, and 8*1.5 is 12.
now apply this to AC to find RT
AC=15
15*(2/3)=10
10*1.5=15
RT =10
