Step 1: Add the parts of the ratio
Ratio = 2 : 7, total parts = \( 2 + 7 = 9 \)
Step 2: Find the value of one part
Total amount = Rs.21600
Value of 1 part = \( \frac{21600}{9} = 2400 \)
Step 3: Multiply by B's share (7 parts)
B’s share = \( 7 \times 2400 = \boxed{16800} \)