Answer:
b
Step-by-step explanation:
Since the triangles are similar then the ratios of corresponding sides are equal, that is
[tex]\frac{AB}{XY}[/tex] = [tex]\frac{BC}{YZ}[/tex] , substitute values
[tex]\frac{15}{10}[/tex] = [tex]\frac{21}{YZ}[/tex] ( cross- multiply )
15YZ = 210 ( divide both sides by 15 )
YZ = 14 → b
