<p>Page 399 # 11</p>
<p>I need an explanation on how to do this </p>
<p>Page 400 # 16</p>
<p>I need an explanation on how to do this </p>
<p>Page 400 # 17</p>
<p>I need an explanation on how to do this </p>
<p>Page 400 # 18</p>
<p>I need an explanation on how to do this </p>
<p>Page 401 # 19 and 20</p>
<p>I need an explanation on how to do these</p>