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<b>let </b><font color="Maroon">s</font> be  <a href="xreal_0.html#V1" target="_self">real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/><b>let </b><font color="Maroon">t</font> be  <a href="xreal_0.html#V1" target="_self">real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>



<b>assume </b><a NAME="E1:19"/>
<font color="Maroon">s</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">t</font>
 ;<br/>

<a NAME="E2:19"/><b>then </b>
<font color="Maroon">s</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">t</font> <a href="xxreal_0.html#R1">&lt;=</a> <font color="Maroon">t</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">t</font>
 
<b>by </b><i/>;<br/>
<a NAME="E3:19"/><b>then </b>
<span class="p1">(<span class="default"><font color="Maroon">s</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">t</font></span>)</span> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">s</font> <a href="xxreal_0.html#R1">&lt;=</a> 0 <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">s</font>
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:19"/>
 <a href="xcmplx_0.html#K4">-</a> <font color="Maroon">t</font> <a href="xxreal_0.html#R1">&lt;=</a>  <a href="xcmplx_0.html#K4">-</a> <font color="Maroon">s</font>
 ;<br/>


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