Answer:
b = 54 cm
Step-by-step explanation:
We can use proportions if the shapes are similar
Take the same side lengths over each other.
81 cm b cm
----------- = --------------
24 cm 16 cm
Using cross products
81 *16 = 24*b
Divide each side by 24
81*16/24 = 24b/24
54 =b
