,ORD]$ ,PAIR ,EXAMPLES #A4 ,OP5 P>5!SIS ;X COMMA ;Y CLOSE P>5!SIS IS WRITT5 _% (X, Y) _: #B4 ,OP5 P>5!SIS FIVE COMMA NEGATIVE ?REE CLOSE P>5!SIS IS WRITT5 _% (5, -3) _: #C4 ,OP5 P>5!SIS NEGATIVE "O COMMA Z]O CLOSE P>5!SIS IS WRITT5 _% (-1, 0) _: #D4 ,OP5 P>5!SIS ;X SUB "O COMMA ;Y SUB "O CLOSE P>5!SIS IS WRITT5 _% (X1, Y1) _: #E4 ,OP5 P>5!SIS OP5 FRAC;N ;X SUB "O PLUS ;X SUB TWO OV] TWO CLOSE FRAC;N COMMA OP5 FRAC;N ;Y SUB "O PLUS ;Y SUB TWO OV] TWO CLOSE FRAC;N CLOSE P>5!SIS IS WRITT5 _% (?X1+X2/2#,?Y1+Y2/2#) _: #A