Answer
15%
70
700
Work Step by Step
$\frac{345000-300000}{300000}=\frac{45000}{300000}=0.15=15\%$
$\Delta qty=E_d\times \Delta price$
$\Delta qty=2.0\times15=30\%$
$100-(100\times0.30)=100-30=70$
$70\ boats \times 10\frac{workers}{boat}=700$