You are asking for the condition needed for the
<span>two segments to be perpendicular to each other. </span>
<span>If the slope of one segment is m, then the slope of a perpendicular segment would be -1/m </span>
<span>this means that m2 = -1/m and so m2 x m = -1 </span>
<span>If you look carefully at your choices, the 3rd answer involves the two slope and has the -1. It's </span>
<span>the correct answer.</span>
I believe you do it like this:
1/2 Q+5/2
divide 1/2 into each term
to divide multiply by the reciprocal
1/2 x2/1= 1
5/2 x 2/1=5
1/2(Q+5)