Answer:
6%
Step-by-step explanation:
Calculation for ECE's market-to-book ratio 
Using this formula
Market-to-book ratio = (MV Equity)/(BV Equity) 
Let plug in the formula
Market-to-book ratio = ($24 x 25 million)/100 million 
Market-to-book ratio = 6%
Therefore ECE's market-to-book ratio is closest to 6%